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2880 lines
74 KiB
2880 lines
74 KiB
// SPDX-License-Identifier: GPL-2.0-only |
|
/* |
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* linux/fs/locks.c |
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* |
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* We implement four types of file locks: BSD locks, posix locks, open |
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* file description locks, and leases. For details about BSD locks, |
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* see the flock(2) man page; for details about the other three, see |
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* fcntl(2). |
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* |
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* |
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* Locking conflicts and dependencies: |
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* If multiple threads attempt to lock the same byte (or flock the same file) |
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* only one can be granted the lock, and other must wait their turn. |
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* The first lock has been "applied" or "granted", the others are "waiting" |
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* and are "blocked" by the "applied" lock.. |
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* |
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* Waiting and applied locks are all kept in trees whose properties are: |
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* |
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* - the root of a tree may be an applied or waiting lock. |
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* - every other node in the tree is a waiting lock that |
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* conflicts with every ancestor of that node. |
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* |
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* Every such tree begins life as a waiting singleton which obviously |
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* satisfies the above properties. |
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* |
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* The only ways we modify trees preserve these properties: |
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* |
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* 1. We may add a new leaf node, but only after first verifying that it |
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* conflicts with all of its ancestors. |
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* 2. We may remove the root of a tree, creating a new singleton |
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* tree from the root and N new trees rooted in the immediate |
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* children. |
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* 3. If the root of a tree is not currently an applied lock, we may |
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* apply it (if possible). |
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* 4. We may upgrade the root of the tree (either extend its range, |
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* or upgrade its entire range from read to write). |
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* |
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* When an applied lock is modified in a way that reduces or downgrades any |
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* part of its range, we remove all its children (2 above). This particularly |
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* happens when a lock is unlocked. |
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* |
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* For each of those child trees we "wake up" the thread which is |
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* waiting for the lock so it can continue handling as follows: if the |
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* root of the tree applies, we do so (3). If it doesn't, it must |
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* conflict with some applied lock. We remove (wake up) all of its children |
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* (2), and add it is a new leaf to the tree rooted in the applied |
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* lock (1). We then repeat the process recursively with those |
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* children. |
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* |
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*/ |
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|
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#include <linux/capability.h> |
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#include <linux/file.h> |
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#include <linux/fdtable.h> |
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#include <linux/fs.h> |
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#include <linux/init.h> |
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#include <linux/security.h> |
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#include <linux/slab.h> |
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#include <linux/syscalls.h> |
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#include <linux/time.h> |
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#include <linux/rcupdate.h> |
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#include <linux/pid_namespace.h> |
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#include <linux/hashtable.h> |
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#include <linux/percpu.h> |
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#include <linux/sysctl.h> |
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|
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#define CREATE_TRACE_POINTS |
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#include <trace/events/filelock.h> |
|
|
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#include <linux/uaccess.h> |
|
|
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#define IS_POSIX(fl) (fl->fl_flags & FL_POSIX) |
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#define IS_FLOCK(fl) (fl->fl_flags & FL_FLOCK) |
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#define IS_LEASE(fl) (fl->fl_flags & (FL_LEASE|FL_DELEG|FL_LAYOUT)) |
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#define IS_OFDLCK(fl) (fl->fl_flags & FL_OFDLCK) |
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#define IS_REMOTELCK(fl) (fl->fl_pid <= 0) |
|
|
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static bool lease_breaking(struct file_lock *fl) |
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{ |
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return fl->fl_flags & (FL_UNLOCK_PENDING | FL_DOWNGRADE_PENDING); |
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} |
|
|
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static int target_leasetype(struct file_lock *fl) |
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{ |
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if (fl->fl_flags & FL_UNLOCK_PENDING) |
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return F_UNLCK; |
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if (fl->fl_flags & FL_DOWNGRADE_PENDING) |
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return F_RDLCK; |
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return fl->fl_type; |
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} |
|
|
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static int leases_enable = 1; |
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static int lease_break_time = 45; |
|
|
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#ifdef CONFIG_SYSCTL |
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static struct ctl_table locks_sysctls[] = { |
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{ |
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.procname = "leases-enable", |
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.data = &leases_enable, |
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.maxlen = sizeof(int), |
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.mode = 0644, |
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.proc_handler = proc_dointvec, |
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}, |
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#ifdef CONFIG_MMU |
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{ |
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.procname = "lease-break-time", |
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.data = &lease_break_time, |
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.maxlen = sizeof(int), |
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.mode = 0644, |
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.proc_handler = proc_dointvec, |
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}, |
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#endif /* CONFIG_MMU */ |
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{} |
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}; |
|
|
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static int __init init_fs_locks_sysctls(void) |
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{ |
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register_sysctl_init("fs", locks_sysctls); |
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return 0; |
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} |
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early_initcall(init_fs_locks_sysctls); |
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#endif /* CONFIG_SYSCTL */ |
|
|
|
/* |
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* The global file_lock_list is only used for displaying /proc/locks, so we |
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* keep a list on each CPU, with each list protected by its own spinlock. |
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* Global serialization is done using file_rwsem. |
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* |
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* Note that alterations to the list also require that the relevant flc_lock is |
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* held. |
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*/ |
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struct file_lock_list_struct { |
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spinlock_t lock; |
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struct hlist_head hlist; |
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}; |
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static DEFINE_PER_CPU(struct file_lock_list_struct, file_lock_list); |
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DEFINE_STATIC_PERCPU_RWSEM(file_rwsem); |
|
|
|
|
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/* |
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* The blocked_hash is used to find POSIX lock loops for deadlock detection. |
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* It is protected by blocked_lock_lock. |
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* |
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* We hash locks by lockowner in order to optimize searching for the lock a |
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* particular lockowner is waiting on. |
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* |
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* FIXME: make this value scale via some heuristic? We generally will want more |
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* buckets when we have more lockowners holding locks, but that's a little |
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* difficult to determine without knowing what the workload will look like. |
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*/ |
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#define BLOCKED_HASH_BITS 7 |
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static DEFINE_HASHTABLE(blocked_hash, BLOCKED_HASH_BITS); |
|
|
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/* |
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* This lock protects the blocked_hash. Generally, if you're accessing it, you |
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* want to be holding this lock. |
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* |
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* In addition, it also protects the fl->fl_blocked_requests list, and the |
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* fl->fl_blocker pointer for file_lock structures that are acting as lock |
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* requests (in contrast to those that are acting as records of acquired locks). |
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* |
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* Note that when we acquire this lock in order to change the above fields, |
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* we often hold the flc_lock as well. In certain cases, when reading the fields |
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* protected by this lock, we can skip acquiring it iff we already hold the |
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* flc_lock. |
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*/ |
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static DEFINE_SPINLOCK(blocked_lock_lock); |
|
|
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static struct kmem_cache *flctx_cache __read_mostly; |
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static struct kmem_cache *filelock_cache __read_mostly; |
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|
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static struct file_lock_context * |
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locks_get_lock_context(struct inode *inode, int type) |
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{ |
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struct file_lock_context *ctx; |
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|
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/* paired with cmpxchg() below */ |
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ctx = smp_load_acquire(&inode->i_flctx); |
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if (likely(ctx) || type == F_UNLCK) |
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goto out; |
|
|
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ctx = kmem_cache_alloc(flctx_cache, GFP_KERNEL); |
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if (!ctx) |
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goto out; |
|
|
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spin_lock_init(&ctx->flc_lock); |
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INIT_LIST_HEAD(&ctx->flc_flock); |
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INIT_LIST_HEAD(&ctx->flc_posix); |
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INIT_LIST_HEAD(&ctx->flc_lease); |
|
|
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/* |
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* Assign the pointer if it's not already assigned. If it is, then |
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* free the context we just allocated. |
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*/ |
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if (cmpxchg(&inode->i_flctx, NULL, ctx)) { |
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kmem_cache_free(flctx_cache, ctx); |
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ctx = smp_load_acquire(&inode->i_flctx); |
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} |
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out: |
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trace_locks_get_lock_context(inode, type, ctx); |
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return ctx; |
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} |
|
|
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static void |
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locks_dump_ctx_list(struct list_head *list, char *list_type) |
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{ |
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struct file_lock *fl; |
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|
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list_for_each_entry(fl, list, fl_list) { |
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pr_warn("%s: fl_owner=%p fl_flags=0x%x fl_type=0x%x fl_pid=%u\n", list_type, fl->fl_owner, fl->fl_flags, fl->fl_type, fl->fl_pid); |
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} |
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} |
|
|
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static void |
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locks_check_ctx_lists(struct inode *inode) |
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{ |
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struct file_lock_context *ctx = inode->i_flctx; |
|
|
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if (unlikely(!list_empty(&ctx->flc_flock) || |
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!list_empty(&ctx->flc_posix) || |
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!list_empty(&ctx->flc_lease))) { |
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pr_warn("Leaked locks on dev=0x%x:0x%x ino=0x%lx:\n", |
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MAJOR(inode->i_sb->s_dev), MINOR(inode->i_sb->s_dev), |
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inode->i_ino); |
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locks_dump_ctx_list(&ctx->flc_flock, "FLOCK"); |
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locks_dump_ctx_list(&ctx->flc_posix, "POSIX"); |
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locks_dump_ctx_list(&ctx->flc_lease, "LEASE"); |
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} |
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} |
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|
|
static void |
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locks_check_ctx_file_list(struct file *filp, struct list_head *list, |
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char *list_type) |
|
{ |
|
struct file_lock *fl; |
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struct inode *inode = locks_inode(filp); |
|
|
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list_for_each_entry(fl, list, fl_list) |
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if (fl->fl_file == filp) |
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pr_warn("Leaked %s lock on dev=0x%x:0x%x ino=0x%lx " |
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" fl_owner=%p fl_flags=0x%x fl_type=0x%x fl_pid=%u\n", |
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list_type, MAJOR(inode->i_sb->s_dev), |
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MINOR(inode->i_sb->s_dev), inode->i_ino, |
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fl->fl_owner, fl->fl_flags, fl->fl_type, fl->fl_pid); |
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} |
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|
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void |
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locks_free_lock_context(struct inode *inode) |
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{ |
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struct file_lock_context *ctx = inode->i_flctx; |
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|
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if (unlikely(ctx)) { |
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locks_check_ctx_lists(inode); |
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kmem_cache_free(flctx_cache, ctx); |
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} |
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} |
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|
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static void locks_init_lock_heads(struct file_lock *fl) |
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{ |
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INIT_HLIST_NODE(&fl->fl_link); |
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INIT_LIST_HEAD(&fl->fl_list); |
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INIT_LIST_HEAD(&fl->fl_blocked_requests); |
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INIT_LIST_HEAD(&fl->fl_blocked_member); |
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init_waitqueue_head(&fl->fl_wait); |
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} |
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|
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/* Allocate an empty lock structure. */ |
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struct file_lock *locks_alloc_lock(void) |
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{ |
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struct file_lock *fl = kmem_cache_zalloc(filelock_cache, GFP_KERNEL); |
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|
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if (fl) |
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locks_init_lock_heads(fl); |
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|
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return fl; |
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} |
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EXPORT_SYMBOL_GPL(locks_alloc_lock); |
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|
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void locks_release_private(struct file_lock *fl) |
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{ |
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BUG_ON(waitqueue_active(&fl->fl_wait)); |
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BUG_ON(!list_empty(&fl->fl_list)); |
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BUG_ON(!list_empty(&fl->fl_blocked_requests)); |
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BUG_ON(!list_empty(&fl->fl_blocked_member)); |
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BUG_ON(!hlist_unhashed(&fl->fl_link)); |
|
|
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if (fl->fl_ops) { |
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if (fl->fl_ops->fl_release_private) |
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fl->fl_ops->fl_release_private(fl); |
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fl->fl_ops = NULL; |
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} |
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|
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if (fl->fl_lmops) { |
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if (fl->fl_lmops->lm_put_owner) { |
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fl->fl_lmops->lm_put_owner(fl->fl_owner); |
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fl->fl_owner = NULL; |
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} |
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fl->fl_lmops = NULL; |
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} |
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} |
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EXPORT_SYMBOL_GPL(locks_release_private); |
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|
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/* Free a lock which is not in use. */ |
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void locks_free_lock(struct file_lock *fl) |
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{ |
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locks_release_private(fl); |
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kmem_cache_free(filelock_cache, fl); |
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} |
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EXPORT_SYMBOL(locks_free_lock); |
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|
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static void |
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locks_dispose_list(struct list_head *dispose) |
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{ |
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struct file_lock *fl; |
|
|
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while (!list_empty(dispose)) { |
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fl = list_first_entry(dispose, struct file_lock, fl_list); |
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list_del_init(&fl->fl_list); |
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locks_free_lock(fl); |
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} |
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} |
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|
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void locks_init_lock(struct file_lock *fl) |
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{ |
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memset(fl, 0, sizeof(struct file_lock)); |
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locks_init_lock_heads(fl); |
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} |
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EXPORT_SYMBOL(locks_init_lock); |
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|
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/* |
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* Initialize a new lock from an existing file_lock structure. |
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*/ |
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void locks_copy_conflock(struct file_lock *new, struct file_lock *fl) |
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{ |
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new->fl_owner = fl->fl_owner; |
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new->fl_pid = fl->fl_pid; |
|
new->fl_file = NULL; |
|
new->fl_flags = fl->fl_flags; |
|
new->fl_type = fl->fl_type; |
|
new->fl_start = fl->fl_start; |
|
new->fl_end = fl->fl_end; |
|
new->fl_lmops = fl->fl_lmops; |
|
new->fl_ops = NULL; |
|
|
|
if (fl->fl_lmops) { |
|
if (fl->fl_lmops->lm_get_owner) |
|
fl->fl_lmops->lm_get_owner(fl->fl_owner); |
|
} |
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} |
|
EXPORT_SYMBOL(locks_copy_conflock); |
|
|
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void locks_copy_lock(struct file_lock *new, struct file_lock *fl) |
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{ |
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/* "new" must be a freshly-initialized lock */ |
|
WARN_ON_ONCE(new->fl_ops); |
|
|
|
locks_copy_conflock(new, fl); |
|
|
|
new->fl_file = fl->fl_file; |
|
new->fl_ops = fl->fl_ops; |
|
|
|
if (fl->fl_ops) { |
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if (fl->fl_ops->fl_copy_lock) |
|
fl->fl_ops->fl_copy_lock(new, fl); |
|
} |
|
} |
|
EXPORT_SYMBOL(locks_copy_lock); |
|
|
|
static void locks_move_blocks(struct file_lock *new, struct file_lock *fl) |
|
{ |
|
struct file_lock *f; |
|
|
|
/* |
|
* As ctx->flc_lock is held, new requests cannot be added to |
|
* ->fl_blocked_requests, so we don't need a lock to check if it |
|
* is empty. |
|
*/ |
|
if (list_empty(&fl->fl_blocked_requests)) |
|
return; |
|
spin_lock(&blocked_lock_lock); |
|
list_splice_init(&fl->fl_blocked_requests, &new->fl_blocked_requests); |
|
list_for_each_entry(f, &new->fl_blocked_requests, fl_blocked_member) |
|
f->fl_blocker = new; |
|
spin_unlock(&blocked_lock_lock); |
|
} |
|
|
|
static inline int flock_translate_cmd(int cmd) { |
|
switch (cmd) { |
|
case LOCK_SH: |
|
return F_RDLCK; |
|
case LOCK_EX: |
|
return F_WRLCK; |
|
case LOCK_UN: |
|
return F_UNLCK; |
|
} |
|
return -EINVAL; |
|
} |
|
|
|
/* Fill in a file_lock structure with an appropriate FLOCK lock. */ |
|
static struct file_lock * |
|
flock_make_lock(struct file *filp, unsigned int cmd, struct file_lock *fl) |
|
{ |
|
int type = flock_translate_cmd(cmd); |
|
|
|
if (type < 0) |
|
return ERR_PTR(type); |
|
|
|
if (fl == NULL) { |
|
fl = locks_alloc_lock(); |
|
if (fl == NULL) |
|
return ERR_PTR(-ENOMEM); |
|
} else { |
|
locks_init_lock(fl); |
|
} |
|
|
|
fl->fl_file = filp; |
|
fl->fl_owner = filp; |
|
fl->fl_pid = current->tgid; |
|
fl->fl_flags = FL_FLOCK; |
|
fl->fl_type = type; |
|
fl->fl_end = OFFSET_MAX; |
|
|
|
return fl; |
|
} |
|
|
|
static int assign_type(struct file_lock *fl, long type) |
|
{ |
|
switch (type) { |
|
case F_RDLCK: |
|
case F_WRLCK: |
|
case F_UNLCK: |
|
fl->fl_type = type; |
|
break; |
|
default: |
|
return -EINVAL; |
|
} |
|
return 0; |
|
} |
|
|
|
static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl, |
|
struct flock64 *l) |
|
{ |
|
switch (l->l_whence) { |
|
case SEEK_SET: |
|
fl->fl_start = 0; |
|
break; |
|
case SEEK_CUR: |
|
fl->fl_start = filp->f_pos; |
|
break; |
|
case SEEK_END: |
|
fl->fl_start = i_size_read(file_inode(filp)); |
|
break; |
|
default: |
|
return -EINVAL; |
|
} |
|
if (l->l_start > OFFSET_MAX - fl->fl_start) |
|
return -EOVERFLOW; |
|
fl->fl_start += l->l_start; |
|
if (fl->fl_start < 0) |
|
return -EINVAL; |
|
|
|
/* POSIX-1996 leaves the case l->l_len < 0 undefined; |
|
POSIX-2001 defines it. */ |
|
if (l->l_len > 0) { |
|
if (l->l_len - 1 > OFFSET_MAX - fl->fl_start) |
|
return -EOVERFLOW; |
|
fl->fl_end = fl->fl_start + (l->l_len - 1); |
|
|
|
} else if (l->l_len < 0) { |
|
if (fl->fl_start + l->l_len < 0) |
|
return -EINVAL; |
|
fl->fl_end = fl->fl_start - 1; |
|
fl->fl_start += l->l_len; |
|
} else |
|
fl->fl_end = OFFSET_MAX; |
|
|
|
fl->fl_owner = current->files; |
|
fl->fl_pid = current->tgid; |
|
fl->fl_file = filp; |
|
fl->fl_flags = FL_POSIX; |
|
fl->fl_ops = NULL; |
|
fl->fl_lmops = NULL; |
|
|
|
return assign_type(fl, l->l_type); |
|
} |
|
|
|
/* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX |
|
* style lock. |
|
*/ |
|
static int flock_to_posix_lock(struct file *filp, struct file_lock *fl, |
|
struct flock *l) |
|
{ |
|
struct flock64 ll = { |
|
.l_type = l->l_type, |
|
.l_whence = l->l_whence, |
|
.l_start = l->l_start, |
|
.l_len = l->l_len, |
|
}; |
|
|
|
return flock64_to_posix_lock(filp, fl, &ll); |
|
} |
|
|
|
/* default lease lock manager operations */ |
|
static bool |
|
lease_break_callback(struct file_lock *fl) |
|
{ |
|
kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG); |
|
return false; |
|
} |
|
|
|
static void |
|
lease_setup(struct file_lock *fl, void **priv) |
|
{ |
|
struct file *filp = fl->fl_file; |
|
struct fasync_struct *fa = *priv; |
|
|
|
/* |
|
* fasync_insert_entry() returns the old entry if any. If there was no |
|
* old entry, then it used "priv" and inserted it into the fasync list. |
|
* Clear the pointer to indicate that it shouldn't be freed. |
|
*/ |
|
if (!fasync_insert_entry(fa->fa_fd, filp, &fl->fl_fasync, fa)) |
|
*priv = NULL; |
|
|
|
__f_setown(filp, task_pid(current), PIDTYPE_TGID, 0); |
|
} |
|
|
|
static const struct lock_manager_operations lease_manager_ops = { |
|
.lm_break = lease_break_callback, |
|
.lm_change = lease_modify, |
|
.lm_setup = lease_setup, |
|
}; |
|
|
|
/* |
|
* Initialize a lease, use the default lock manager operations |
|
*/ |
|
static int lease_init(struct file *filp, long type, struct file_lock *fl) |
|
{ |
|
if (assign_type(fl, type) != 0) |
|
return -EINVAL; |
|
|
|
fl->fl_owner = filp; |
|
fl->fl_pid = current->tgid; |
|
|
|
fl->fl_file = filp; |
|
fl->fl_flags = FL_LEASE; |
|
fl->fl_start = 0; |
|
fl->fl_end = OFFSET_MAX; |
|
fl->fl_ops = NULL; |
|
fl->fl_lmops = &lease_manager_ops; |
|
return 0; |
|
} |
|
|
|
/* Allocate a file_lock initialised to this type of lease */ |
|
static struct file_lock *lease_alloc(struct file *filp, long type) |
|
{ |
|
struct file_lock *fl = locks_alloc_lock(); |
|
int error = -ENOMEM; |
|
|
|
if (fl == NULL) |
|
return ERR_PTR(error); |
|
|
|
error = lease_init(filp, type, fl); |
|
if (error) { |
|
locks_free_lock(fl); |
|
return ERR_PTR(error); |
|
} |
|
return fl; |
|
} |
|
|
|
/* Check if two locks overlap each other. |
|
*/ |
|
static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2) |
|
{ |
|
return ((fl1->fl_end >= fl2->fl_start) && |
|
(fl2->fl_end >= fl1->fl_start)); |
|
} |
|
|
|
/* |
|
* Check whether two locks have the same owner. |
|
*/ |
|
static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2) |
|
{ |
|
return fl1->fl_owner == fl2->fl_owner; |
|
} |
|
|
|
/* Must be called with the flc_lock held! */ |
|
static void locks_insert_global_locks(struct file_lock *fl) |
|
{ |
|
struct file_lock_list_struct *fll = this_cpu_ptr(&file_lock_list); |
|
|
|
percpu_rwsem_assert_held(&file_rwsem); |
|
|
|
spin_lock(&fll->lock); |
|
fl->fl_link_cpu = smp_processor_id(); |
|
hlist_add_head(&fl->fl_link, &fll->hlist); |
|
spin_unlock(&fll->lock); |
|
} |
|
|
|
/* Must be called with the flc_lock held! */ |
|
static void locks_delete_global_locks(struct file_lock *fl) |
|
{ |
|
struct file_lock_list_struct *fll; |
|
|
|
percpu_rwsem_assert_held(&file_rwsem); |
|
|
|
/* |
|
* Avoid taking lock if already unhashed. This is safe since this check |
|
* is done while holding the flc_lock, and new insertions into the list |
|
* also require that it be held. |
|
*/ |
|
if (hlist_unhashed(&fl->fl_link)) |
|
return; |
|
|
|
fll = per_cpu_ptr(&file_lock_list, fl->fl_link_cpu); |
|
spin_lock(&fll->lock); |
|
hlist_del_init(&fl->fl_link); |
|
spin_unlock(&fll->lock); |
|
} |
|
|
|
static unsigned long |
|
posix_owner_key(struct file_lock *fl) |
|
{ |
|
return (unsigned long)fl->fl_owner; |
|
} |
|
|
|
static void locks_insert_global_blocked(struct file_lock *waiter) |
|
{ |
|
lockdep_assert_held(&blocked_lock_lock); |
|
|
|
hash_add(blocked_hash, &waiter->fl_link, posix_owner_key(waiter)); |
|
} |
|
|
|
static void locks_delete_global_blocked(struct file_lock *waiter) |
|
{ |
|
lockdep_assert_held(&blocked_lock_lock); |
|
|
|
hash_del(&waiter->fl_link); |
|
} |
|
|
|
/* Remove waiter from blocker's block list. |
|
* When blocker ends up pointing to itself then the list is empty. |
|
* |
|
* Must be called with blocked_lock_lock held. |
|
*/ |
|
static void __locks_delete_block(struct file_lock *waiter) |
|
{ |
|
locks_delete_global_blocked(waiter); |
|
list_del_init(&waiter->fl_blocked_member); |
|
} |
|
|
|
static void __locks_wake_up_blocks(struct file_lock *blocker) |
|
{ |
|
while (!list_empty(&blocker->fl_blocked_requests)) { |
|
struct file_lock *waiter; |
|
|
|
waiter = list_first_entry(&blocker->fl_blocked_requests, |
|
struct file_lock, fl_blocked_member); |
|
__locks_delete_block(waiter); |
|
if (waiter->fl_lmops && waiter->fl_lmops->lm_notify) |
|
waiter->fl_lmops->lm_notify(waiter); |
|
else |
|
wake_up(&waiter->fl_wait); |
|
|
|
/* |
|
* The setting of fl_blocker to NULL marks the "done" |
|
* point in deleting a block. Paired with acquire at the top |
|
* of locks_delete_block(). |
|
*/ |
|
smp_store_release(&waiter->fl_blocker, NULL); |
|
} |
|
} |
|
|
|
/** |
|
* locks_delete_block - stop waiting for a file lock |
|
* @waiter: the lock which was waiting |
|
* |
|
* lockd/nfsd need to disconnect the lock while working on it. |
|
*/ |
|
int locks_delete_block(struct file_lock *waiter) |
|
{ |
|
int status = -ENOENT; |
|
|
|
/* |
|
* If fl_blocker is NULL, it won't be set again as this thread "owns" |
|
* the lock and is the only one that might try to claim the lock. |
|
* |
|
* We use acquire/release to manage fl_blocker so that we can |
|
* optimize away taking the blocked_lock_lock in many cases. |
|
* |
|
* The smp_load_acquire guarantees two things: |
|
* |
|
* 1/ that fl_blocked_requests can be tested locklessly. If something |
|
* was recently added to that list it must have been in a locked region |
|
* *before* the locked region when fl_blocker was set to NULL. |
|
* |
|
* 2/ that no other thread is accessing 'waiter', so it is safe to free |
|
* it. __locks_wake_up_blocks is careful not to touch waiter after |
|
* fl_blocker is released. |
|
* |
|
* If a lockless check of fl_blocker shows it to be NULL, we know that |
|
* no new locks can be inserted into its fl_blocked_requests list, and |
|
* can avoid doing anything further if the list is empty. |
|
*/ |
|
if (!smp_load_acquire(&waiter->fl_blocker) && |
|
list_empty(&waiter->fl_blocked_requests)) |
|
return status; |
|
|
|
spin_lock(&blocked_lock_lock); |
|
if (waiter->fl_blocker) |
|
status = 0; |
|
__locks_wake_up_blocks(waiter); |
|
__locks_delete_block(waiter); |
|
|
|
/* |
|
* The setting of fl_blocker to NULL marks the "done" point in deleting |
|
* a block. Paired with acquire at the top of this function. |
|
*/ |
|
smp_store_release(&waiter->fl_blocker, NULL); |
|
spin_unlock(&blocked_lock_lock); |
|
return status; |
|
} |
|
EXPORT_SYMBOL(locks_delete_block); |
|
|
|
/* Insert waiter into blocker's block list. |
|
* We use a circular list so that processes can be easily woken up in |
|
* the order they blocked. The documentation doesn't require this but |
|
* it seems like the reasonable thing to do. |
|
* |
|
* Must be called with both the flc_lock and blocked_lock_lock held. The |
|
* fl_blocked_requests list itself is protected by the blocked_lock_lock, |
|
* but by ensuring that the flc_lock is also held on insertions we can avoid |
|
* taking the blocked_lock_lock in some cases when we see that the |
|
* fl_blocked_requests list is empty. |
|
* |
|
* Rather than just adding to the list, we check for conflicts with any existing |
|
* waiters, and add beneath any waiter that blocks the new waiter. |
|
* Thus wakeups don't happen until needed. |
|
*/ |
|
static void __locks_insert_block(struct file_lock *blocker, |
|
struct file_lock *waiter, |
|
bool conflict(struct file_lock *, |
|
struct file_lock *)) |
|
{ |
|
struct file_lock *fl; |
|
BUG_ON(!list_empty(&waiter->fl_blocked_member)); |
|
|
|
new_blocker: |
|
list_for_each_entry(fl, &blocker->fl_blocked_requests, fl_blocked_member) |
|
if (conflict(fl, waiter)) { |
|
blocker = fl; |
|
goto new_blocker; |
|
} |
|
waiter->fl_blocker = blocker; |
|
list_add_tail(&waiter->fl_blocked_member, &blocker->fl_blocked_requests); |
|
if (IS_POSIX(blocker) && !IS_OFDLCK(blocker)) |
|
locks_insert_global_blocked(waiter); |
|
|
|
/* The requests in waiter->fl_blocked are known to conflict with |
|
* waiter, but might not conflict with blocker, or the requests |
|
* and lock which block it. So they all need to be woken. |
|
*/ |
|
__locks_wake_up_blocks(waiter); |
|
} |
|
|
|
/* Must be called with flc_lock held. */ |
|
static void locks_insert_block(struct file_lock *blocker, |
|
struct file_lock *waiter, |
|
bool conflict(struct file_lock *, |
|
struct file_lock *)) |
|
{ |
|
spin_lock(&blocked_lock_lock); |
|
__locks_insert_block(blocker, waiter, conflict); |
|
spin_unlock(&blocked_lock_lock); |
|
} |
|
|
|
/* |
|
* Wake up processes blocked waiting for blocker. |
|
* |
|
* Must be called with the inode->flc_lock held! |
|
*/ |
|
static void locks_wake_up_blocks(struct file_lock *blocker) |
|
{ |
|
/* |
|
* Avoid taking global lock if list is empty. This is safe since new |
|
* blocked requests are only added to the list under the flc_lock, and |
|
* the flc_lock is always held here. Note that removal from the |
|
* fl_blocked_requests list does not require the flc_lock, so we must |
|
* recheck list_empty() after acquiring the blocked_lock_lock. |
|
*/ |
|
if (list_empty(&blocker->fl_blocked_requests)) |
|
return; |
|
|
|
spin_lock(&blocked_lock_lock); |
|
__locks_wake_up_blocks(blocker); |
|
spin_unlock(&blocked_lock_lock); |
|
} |
|
|
|
static void |
|
locks_insert_lock_ctx(struct file_lock *fl, struct list_head *before) |
|
{ |
|
list_add_tail(&fl->fl_list, before); |
|
locks_insert_global_locks(fl); |
|
} |
|
|
|
static void |
|
locks_unlink_lock_ctx(struct file_lock *fl) |
|
{ |
|
locks_delete_global_locks(fl); |
|
list_del_init(&fl->fl_list); |
|
locks_wake_up_blocks(fl); |
|
} |
|
|
|
static void |
|
locks_delete_lock_ctx(struct file_lock *fl, struct list_head *dispose) |
|
{ |
|
locks_unlink_lock_ctx(fl); |
|
if (dispose) |
|
list_add(&fl->fl_list, dispose); |
|
else |
|
locks_free_lock(fl); |
|
} |
|
|
|
/* Determine if lock sys_fl blocks lock caller_fl. Common functionality |
|
* checks for shared/exclusive status of overlapping locks. |
|
*/ |
|
static bool locks_conflict(struct file_lock *caller_fl, |
|
struct file_lock *sys_fl) |
|
{ |
|
if (sys_fl->fl_type == F_WRLCK) |
|
return true; |
|
if (caller_fl->fl_type == F_WRLCK) |
|
return true; |
|
return false; |
|
} |
|
|
|
/* Determine if lock sys_fl blocks lock caller_fl. POSIX specific |
|
* checking before calling the locks_conflict(). |
|
*/ |
|
static bool posix_locks_conflict(struct file_lock *caller_fl, |
|
struct file_lock *sys_fl) |
|
{ |
|
/* POSIX locks owned by the same process do not conflict with |
|
* each other. |
|
*/ |
|
if (posix_same_owner(caller_fl, sys_fl)) |
|
return false; |
|
|
|
/* Check whether they overlap */ |
|
if (!locks_overlap(caller_fl, sys_fl)) |
|
return false; |
|
|
|
return locks_conflict(caller_fl, sys_fl); |
|
} |
|
|
|
/* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific |
|
* checking before calling the locks_conflict(). |
|
*/ |
|
static bool flock_locks_conflict(struct file_lock *caller_fl, |
|
struct file_lock *sys_fl) |
|
{ |
|
/* FLOCK locks referring to the same filp do not conflict with |
|
* each other. |
|
*/ |
|
if (caller_fl->fl_file == sys_fl->fl_file) |
|
return false; |
|
|
|
return locks_conflict(caller_fl, sys_fl); |
|
} |
|
|
|
void |
|
posix_test_lock(struct file *filp, struct file_lock *fl) |
|
{ |
|
struct file_lock *cfl; |
|
struct file_lock_context *ctx; |
|
struct inode *inode = locks_inode(filp); |
|
|
|
ctx = smp_load_acquire(&inode->i_flctx); |
|
if (!ctx || list_empty_careful(&ctx->flc_posix)) { |
|
fl->fl_type = F_UNLCK; |
|
return; |
|
} |
|
|
|
spin_lock(&ctx->flc_lock); |
|
list_for_each_entry(cfl, &ctx->flc_posix, fl_list) { |
|
if (posix_locks_conflict(fl, cfl)) { |
|
locks_copy_conflock(fl, cfl); |
|
goto out; |
|
} |
|
} |
|
fl->fl_type = F_UNLCK; |
|
out: |
|
spin_unlock(&ctx->flc_lock); |
|
return; |
|
} |
|
EXPORT_SYMBOL(posix_test_lock); |
|
|
|
/* |
|
* Deadlock detection: |
|
* |
|
* We attempt to detect deadlocks that are due purely to posix file |
|
* locks. |
|
* |
|
* We assume that a task can be waiting for at most one lock at a time. |
|
* So for any acquired lock, the process holding that lock may be |
|
* waiting on at most one other lock. That lock in turns may be held by |
|
* someone waiting for at most one other lock. Given a requested lock |
|
* caller_fl which is about to wait for a conflicting lock block_fl, we |
|
* follow this chain of waiters to ensure we are not about to create a |
|
* cycle. |
|
* |
|
* Since we do this before we ever put a process to sleep on a lock, we |
|
* are ensured that there is never a cycle; that is what guarantees that |
|
* the while() loop in posix_locks_deadlock() eventually completes. |
|
* |
|
* Note: the above assumption may not be true when handling lock |
|
* requests from a broken NFS client. It may also fail in the presence |
|
* of tasks (such as posix threads) sharing the same open file table. |
|
* To handle those cases, we just bail out after a few iterations. |
|
* |
|
* For FL_OFDLCK locks, the owner is the filp, not the files_struct. |
|
* Because the owner is not even nominally tied to a thread of |
|
* execution, the deadlock detection below can't reasonably work well. Just |
|
* skip it for those. |
|
* |
|
* In principle, we could do a more limited deadlock detection on FL_OFDLCK |
|
* locks that just checks for the case where two tasks are attempting to |
|
* upgrade from read to write locks on the same inode. |
|
*/ |
|
|
|
#define MAX_DEADLK_ITERATIONS 10 |
|
|
|
/* Find a lock that the owner of the given block_fl is blocking on. */ |
|
static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl) |
|
{ |
|
struct file_lock *fl; |
|
|
|
hash_for_each_possible(blocked_hash, fl, fl_link, posix_owner_key(block_fl)) { |
|
if (posix_same_owner(fl, block_fl)) { |
|
while (fl->fl_blocker) |
|
fl = fl->fl_blocker; |
|
return fl; |
|
} |
|
} |
|
return NULL; |
|
} |
|
|
|
/* Must be called with the blocked_lock_lock held! */ |
|
static int posix_locks_deadlock(struct file_lock *caller_fl, |
|
struct file_lock *block_fl) |
|
{ |
|
int i = 0; |
|
|
|
lockdep_assert_held(&blocked_lock_lock); |
|
|
|
/* |
|
* This deadlock detector can't reasonably detect deadlocks with |
|
* FL_OFDLCK locks, since they aren't owned by a process, per-se. |
|
*/ |
|
if (IS_OFDLCK(caller_fl)) |
|
return 0; |
|
|
|
while ((block_fl = what_owner_is_waiting_for(block_fl))) { |
|
if (i++ > MAX_DEADLK_ITERATIONS) |
|
return 0; |
|
if (posix_same_owner(caller_fl, block_fl)) |
|
return 1; |
|
} |
|
return 0; |
|
} |
|
|
|
/* Try to create a FLOCK lock on filp. We always insert new FLOCK locks |
|
* after any leases, but before any posix locks. |
|
* |
|
* Note that if called with an FL_EXISTS argument, the caller may determine |
|
* whether or not a lock was successfully freed by testing the return |
|
* value for -ENOENT. |
|
*/ |
|
static int flock_lock_inode(struct inode *inode, struct file_lock *request) |
|
{ |
|
struct file_lock *new_fl = NULL; |
|
struct file_lock *fl; |
|
struct file_lock_context *ctx; |
|
int error = 0; |
|
bool found = false; |
|
LIST_HEAD(dispose); |
|
|
|
ctx = locks_get_lock_context(inode, request->fl_type); |
|
if (!ctx) { |
|
if (request->fl_type != F_UNLCK) |
|
return -ENOMEM; |
|
return (request->fl_flags & FL_EXISTS) ? -ENOENT : 0; |
|
} |
|
|
|
if (!(request->fl_flags & FL_ACCESS) && (request->fl_type != F_UNLCK)) { |
|
new_fl = locks_alloc_lock(); |
|
if (!new_fl) |
|
return -ENOMEM; |
|
} |
|
|
|
percpu_down_read(&file_rwsem); |
|
spin_lock(&ctx->flc_lock); |
|
if (request->fl_flags & FL_ACCESS) |
|
goto find_conflict; |
|
|
|
list_for_each_entry(fl, &ctx->flc_flock, fl_list) { |
|
if (request->fl_file != fl->fl_file) |
|
continue; |
|
if (request->fl_type == fl->fl_type) |
|
goto out; |
|
found = true; |
|
locks_delete_lock_ctx(fl, &dispose); |
|
break; |
|
} |
|
|
|
if (request->fl_type == F_UNLCK) { |
|
if ((request->fl_flags & FL_EXISTS) && !found) |
|
error = -ENOENT; |
|
goto out; |
|
} |
|
|
|
find_conflict: |
|
list_for_each_entry(fl, &ctx->flc_flock, fl_list) { |
|
if (!flock_locks_conflict(request, fl)) |
|
continue; |
|
error = -EAGAIN; |
|
if (!(request->fl_flags & FL_SLEEP)) |
|
goto out; |
|
error = FILE_LOCK_DEFERRED; |
|
locks_insert_block(fl, request, flock_locks_conflict); |
|
goto out; |
|
} |
|
if (request->fl_flags & FL_ACCESS) |
|
goto out; |
|
locks_copy_lock(new_fl, request); |
|
locks_move_blocks(new_fl, request); |
|
locks_insert_lock_ctx(new_fl, &ctx->flc_flock); |
|
new_fl = NULL; |
|
error = 0; |
|
|
|
out: |
|
spin_unlock(&ctx->flc_lock); |
|
percpu_up_read(&file_rwsem); |
|
if (new_fl) |
|
locks_free_lock(new_fl); |
|
locks_dispose_list(&dispose); |
|
trace_flock_lock_inode(inode, request, error); |
|
return error; |
|
} |
|
|
|
static int posix_lock_inode(struct inode *inode, struct file_lock *request, |
|
struct file_lock *conflock) |
|
{ |
|
struct file_lock *fl, *tmp; |
|
struct file_lock *new_fl = NULL; |
|
struct file_lock *new_fl2 = NULL; |
|
struct file_lock *left = NULL; |
|
struct file_lock *right = NULL; |
|
struct file_lock_context *ctx; |
|
int error; |
|
bool added = false; |
|
LIST_HEAD(dispose); |
|
|
|
ctx = locks_get_lock_context(inode, request->fl_type); |
|
if (!ctx) |
|
return (request->fl_type == F_UNLCK) ? 0 : -ENOMEM; |
|
|
|
/* |
|
* We may need two file_lock structures for this operation, |
|
* so we get them in advance to avoid races. |
|
* |
|
* In some cases we can be sure, that no new locks will be needed |
|
*/ |
|
if (!(request->fl_flags & FL_ACCESS) && |
|
(request->fl_type != F_UNLCK || |
|
request->fl_start != 0 || request->fl_end != OFFSET_MAX)) { |
|
new_fl = locks_alloc_lock(); |
|
new_fl2 = locks_alloc_lock(); |
|
} |
|
|
|
percpu_down_read(&file_rwsem); |
|
spin_lock(&ctx->flc_lock); |
|
/* |
|
* New lock request. Walk all POSIX locks and look for conflicts. If |
|
* there are any, either return error or put the request on the |
|
* blocker's list of waiters and the global blocked_hash. |
|
*/ |
|
if (request->fl_type != F_UNLCK) { |
|
list_for_each_entry(fl, &ctx->flc_posix, fl_list) { |
|
if (!posix_locks_conflict(request, fl)) |
|
continue; |
|
if (conflock) |
|
locks_copy_conflock(conflock, fl); |
|
error = -EAGAIN; |
|
if (!(request->fl_flags & FL_SLEEP)) |
|
goto out; |
|
/* |
|
* Deadlock detection and insertion into the blocked |
|
* locks list must be done while holding the same lock! |
|
*/ |
|
error = -EDEADLK; |
|
spin_lock(&blocked_lock_lock); |
|
/* |
|
* Ensure that we don't find any locks blocked on this |
|
* request during deadlock detection. |
|
*/ |
|
__locks_wake_up_blocks(request); |
|
if (likely(!posix_locks_deadlock(request, fl))) { |
|
error = FILE_LOCK_DEFERRED; |
|
__locks_insert_block(fl, request, |
|
posix_locks_conflict); |
|
} |
|
spin_unlock(&blocked_lock_lock); |
|
goto out; |
|
} |
|
} |
|
|
|
/* If we're just looking for a conflict, we're done. */ |
|
error = 0; |
|
if (request->fl_flags & FL_ACCESS) |
|
goto out; |
|
|
|
/* Find the first old lock with the same owner as the new lock */ |
|
list_for_each_entry(fl, &ctx->flc_posix, fl_list) { |
|
if (posix_same_owner(request, fl)) |
|
break; |
|
} |
|
|
|
/* Process locks with this owner. */ |
|
list_for_each_entry_safe_from(fl, tmp, &ctx->flc_posix, fl_list) { |
|
if (!posix_same_owner(request, fl)) |
|
break; |
|
|
|
/* Detect adjacent or overlapping regions (if same lock type) */ |
|
if (request->fl_type == fl->fl_type) { |
|
/* In all comparisons of start vs end, use |
|
* "start - 1" rather than "end + 1". If end |
|
* is OFFSET_MAX, end + 1 will become negative. |
|
*/ |
|
if (fl->fl_end < request->fl_start - 1) |
|
continue; |
|
/* If the next lock in the list has entirely bigger |
|
* addresses than the new one, insert the lock here. |
|
*/ |
|
if (fl->fl_start - 1 > request->fl_end) |
|
break; |
|
|
|
/* If we come here, the new and old lock are of the |
|
* same type and adjacent or overlapping. Make one |
|
* lock yielding from the lower start address of both |
|
* locks to the higher end address. |
|
*/ |
|
if (fl->fl_start > request->fl_start) |
|
fl->fl_start = request->fl_start; |
|
else |
|
request->fl_start = fl->fl_start; |
|
if (fl->fl_end < request->fl_end) |
|
fl->fl_end = request->fl_end; |
|
else |
|
request->fl_end = fl->fl_end; |
|
if (added) { |
|
locks_delete_lock_ctx(fl, &dispose); |
|
continue; |
|
} |
|
request = fl; |
|
added = true; |
|
} else { |
|
/* Processing for different lock types is a bit |
|
* more complex. |
|
*/ |
|
if (fl->fl_end < request->fl_start) |
|
continue; |
|
if (fl->fl_start > request->fl_end) |
|
break; |
|
if (request->fl_type == F_UNLCK) |
|
added = true; |
|
if (fl->fl_start < request->fl_start) |
|
left = fl; |
|
/* If the next lock in the list has a higher end |
|
* address than the new one, insert the new one here. |
|
*/ |
|
if (fl->fl_end > request->fl_end) { |
|
right = fl; |
|
break; |
|
} |
|
if (fl->fl_start >= request->fl_start) { |
|
/* The new lock completely replaces an old |
|
* one (This may happen several times). |
|
*/ |
|
if (added) { |
|
locks_delete_lock_ctx(fl, &dispose); |
|
continue; |
|
} |
|
/* |
|
* Replace the old lock with new_fl, and |
|
* remove the old one. It's safe to do the |
|
* insert here since we know that we won't be |
|
* using new_fl later, and that the lock is |
|
* just replacing an existing lock. |
|
*/ |
|
error = -ENOLCK; |
|
if (!new_fl) |
|
goto out; |
|
locks_copy_lock(new_fl, request); |
|
locks_move_blocks(new_fl, request); |
|
request = new_fl; |
|
new_fl = NULL; |
|
locks_insert_lock_ctx(request, &fl->fl_list); |
|
locks_delete_lock_ctx(fl, &dispose); |
|
added = true; |
|
} |
|
} |
|
} |
|
|
|
/* |
|
* The above code only modifies existing locks in case of merging or |
|
* replacing. If new lock(s) need to be inserted all modifications are |
|
* done below this, so it's safe yet to bail out. |
|
*/ |
|
error = -ENOLCK; /* "no luck" */ |
|
if (right && left == right && !new_fl2) |
|
goto out; |
|
|
|
error = 0; |
|
if (!added) { |
|
if (request->fl_type == F_UNLCK) { |
|
if (request->fl_flags & FL_EXISTS) |
|
error = -ENOENT; |
|
goto out; |
|
} |
|
|
|
if (!new_fl) { |
|
error = -ENOLCK; |
|
goto out; |
|
} |
|
locks_copy_lock(new_fl, request); |
|
locks_move_blocks(new_fl, request); |
|
locks_insert_lock_ctx(new_fl, &fl->fl_list); |
|
fl = new_fl; |
|
new_fl = NULL; |
|
} |
|
if (right) { |
|
if (left == right) { |
|
/* The new lock breaks the old one in two pieces, |
|
* so we have to use the second new lock. |
|
*/ |
|
left = new_fl2; |
|
new_fl2 = NULL; |
|
locks_copy_lock(left, right); |
|
locks_insert_lock_ctx(left, &fl->fl_list); |
|
} |
|
right->fl_start = request->fl_end + 1; |
|
locks_wake_up_blocks(right); |
|
} |
|
if (left) { |
|
left->fl_end = request->fl_start - 1; |
|
locks_wake_up_blocks(left); |
|
} |
|
out: |
|
spin_unlock(&ctx->flc_lock); |
|
percpu_up_read(&file_rwsem); |
|
/* |
|
* Free any unused locks. |
|
*/ |
|
if (new_fl) |
|
locks_free_lock(new_fl); |
|
if (new_fl2) |
|
locks_free_lock(new_fl2); |
|
locks_dispose_list(&dispose); |
|
trace_posix_lock_inode(inode, request, error); |
|
|
|
return error; |
|
} |
|
|
|
/** |
|
* posix_lock_file - Apply a POSIX-style lock to a file |
|
* @filp: The file to apply the lock to |
|
* @fl: The lock to be applied |
|
* @conflock: Place to return a copy of the conflicting lock, if found. |
|
* |
|
* Add a POSIX style lock to a file. |
|
* We merge adjacent & overlapping locks whenever possible. |
|
* POSIX locks are sorted by owner task, then by starting address |
|
* |
|
* Note that if called with an FL_EXISTS argument, the caller may determine |
|
* whether or not a lock was successfully freed by testing the return |
|
* value for -ENOENT. |
|
*/ |
|
int posix_lock_file(struct file *filp, struct file_lock *fl, |
|
struct file_lock *conflock) |
|
{ |
|
return posix_lock_inode(locks_inode(filp), fl, conflock); |
|
} |
|
EXPORT_SYMBOL(posix_lock_file); |
|
|
|
/** |
|
* posix_lock_inode_wait - Apply a POSIX-style lock to a file |
|
* @inode: inode of file to which lock request should be applied |
|
* @fl: The lock to be applied |
|
* |
|
* Apply a POSIX style lock request to an inode. |
|
*/ |
|
static int posix_lock_inode_wait(struct inode *inode, struct file_lock *fl) |
|
{ |
|
int error; |
|
might_sleep (); |
|
for (;;) { |
|
error = posix_lock_inode(inode, fl, NULL); |
|
if (error != FILE_LOCK_DEFERRED) |
|
break; |
|
error = wait_event_interruptible(fl->fl_wait, |
|
list_empty(&fl->fl_blocked_member)); |
|
if (error) |
|
break; |
|
} |
|
locks_delete_block(fl); |
|
return error; |
|
} |
|
|
|
static void lease_clear_pending(struct file_lock *fl, int arg) |
|
{ |
|
switch (arg) { |
|
case F_UNLCK: |
|
fl->fl_flags &= ~FL_UNLOCK_PENDING; |
|
fallthrough; |
|
case F_RDLCK: |
|
fl->fl_flags &= ~FL_DOWNGRADE_PENDING; |
|
} |
|
} |
|
|
|
/* We already had a lease on this file; just change its type */ |
|
int lease_modify(struct file_lock *fl, int arg, struct list_head *dispose) |
|
{ |
|
int error = assign_type(fl, arg); |
|
|
|
if (error) |
|
return error; |
|
lease_clear_pending(fl, arg); |
|
locks_wake_up_blocks(fl); |
|
if (arg == F_UNLCK) { |
|
struct file *filp = fl->fl_file; |
|
|
|
f_delown(filp); |
|
filp->f_owner.signum = 0; |
|
fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync); |
|
if (fl->fl_fasync != NULL) { |
|
printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync); |
|
fl->fl_fasync = NULL; |
|
} |
|
locks_delete_lock_ctx(fl, dispose); |
|
} |
|
return 0; |
|
} |
|
EXPORT_SYMBOL(lease_modify); |
|
|
|
static bool past_time(unsigned long then) |
|
{ |
|
if (!then) |
|
/* 0 is a special value meaning "this never expires": */ |
|
return false; |
|
return time_after(jiffies, then); |
|
} |
|
|
|
static void time_out_leases(struct inode *inode, struct list_head *dispose) |
|
{ |
|
struct file_lock_context *ctx = inode->i_flctx; |
|
struct file_lock *fl, *tmp; |
|
|
|
lockdep_assert_held(&ctx->flc_lock); |
|
|
|
list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list) { |
|
trace_time_out_leases(inode, fl); |
|
if (past_time(fl->fl_downgrade_time)) |
|
lease_modify(fl, F_RDLCK, dispose); |
|
if (past_time(fl->fl_break_time)) |
|
lease_modify(fl, F_UNLCK, dispose); |
|
} |
|
} |
|
|
|
static bool leases_conflict(struct file_lock *lease, struct file_lock *breaker) |
|
{ |
|
bool rc; |
|
|
|
if (lease->fl_lmops->lm_breaker_owns_lease |
|
&& lease->fl_lmops->lm_breaker_owns_lease(lease)) |
|
return false; |
|
if ((breaker->fl_flags & FL_LAYOUT) != (lease->fl_flags & FL_LAYOUT)) { |
|
rc = false; |
|
goto trace; |
|
} |
|
if ((breaker->fl_flags & FL_DELEG) && (lease->fl_flags & FL_LEASE)) { |
|
rc = false; |
|
goto trace; |
|
} |
|
|
|
rc = locks_conflict(breaker, lease); |
|
trace: |
|
trace_leases_conflict(rc, lease, breaker); |
|
return rc; |
|
} |
|
|
|
static bool |
|
any_leases_conflict(struct inode *inode, struct file_lock *breaker) |
|
{ |
|
struct file_lock_context *ctx = inode->i_flctx; |
|
struct file_lock *fl; |
|
|
|
lockdep_assert_held(&ctx->flc_lock); |
|
|
|
list_for_each_entry(fl, &ctx->flc_lease, fl_list) { |
|
if (leases_conflict(fl, breaker)) |
|
return true; |
|
} |
|
return false; |
|
} |
|
|
|
/** |
|
* __break_lease - revoke all outstanding leases on file |
|
* @inode: the inode of the file to return |
|
* @mode: O_RDONLY: break only write leases; O_WRONLY or O_RDWR: |
|
* break all leases |
|
* @type: FL_LEASE: break leases and delegations; FL_DELEG: break |
|
* only delegations |
|
* |
|
* break_lease (inlined for speed) has checked there already is at least |
|
* some kind of lock (maybe a lease) on this file. Leases are broken on |
|
* a call to open() or truncate(). This function can sleep unless you |
|
* specified %O_NONBLOCK to your open(). |
|
*/ |
|
int __break_lease(struct inode *inode, unsigned int mode, unsigned int type) |
|
{ |
|
int error = 0; |
|
struct file_lock_context *ctx; |
|
struct file_lock *new_fl, *fl, *tmp; |
|
unsigned long break_time; |
|
int want_write = (mode & O_ACCMODE) != O_RDONLY; |
|
LIST_HEAD(dispose); |
|
|
|
new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK); |
|
if (IS_ERR(new_fl)) |
|
return PTR_ERR(new_fl); |
|
new_fl->fl_flags = type; |
|
|
|
/* typically we will check that ctx is non-NULL before calling */ |
|
ctx = smp_load_acquire(&inode->i_flctx); |
|
if (!ctx) { |
|
WARN_ON_ONCE(1); |
|
goto free_lock; |
|
} |
|
|
|
percpu_down_read(&file_rwsem); |
|
spin_lock(&ctx->flc_lock); |
|
|
|
time_out_leases(inode, &dispose); |
|
|
|
if (!any_leases_conflict(inode, new_fl)) |
|
goto out; |
|
|
|
break_time = 0; |
|
if (lease_break_time > 0) { |
|
break_time = jiffies + lease_break_time * HZ; |
|
if (break_time == 0) |
|
break_time++; /* so that 0 means no break time */ |
|
} |
|
|
|
list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list) { |
|
if (!leases_conflict(fl, new_fl)) |
|
continue; |
|
if (want_write) { |
|
if (fl->fl_flags & FL_UNLOCK_PENDING) |
|
continue; |
|
fl->fl_flags |= FL_UNLOCK_PENDING; |
|
fl->fl_break_time = break_time; |
|
} else { |
|
if (lease_breaking(fl)) |
|
continue; |
|
fl->fl_flags |= FL_DOWNGRADE_PENDING; |
|
fl->fl_downgrade_time = break_time; |
|
} |
|
if (fl->fl_lmops->lm_break(fl)) |
|
locks_delete_lock_ctx(fl, &dispose); |
|
} |
|
|
|
if (list_empty(&ctx->flc_lease)) |
|
goto out; |
|
|
|
if (mode & O_NONBLOCK) { |
|
trace_break_lease_noblock(inode, new_fl); |
|
error = -EWOULDBLOCK; |
|
goto out; |
|
} |
|
|
|
restart: |
|
fl = list_first_entry(&ctx->flc_lease, struct file_lock, fl_list); |
|
break_time = fl->fl_break_time; |
|
if (break_time != 0) |
|
break_time -= jiffies; |
|
if (break_time == 0) |
|
break_time++; |
|
locks_insert_block(fl, new_fl, leases_conflict); |
|
trace_break_lease_block(inode, new_fl); |
|
spin_unlock(&ctx->flc_lock); |
|
percpu_up_read(&file_rwsem); |
|
|
|
locks_dispose_list(&dispose); |
|
error = wait_event_interruptible_timeout(new_fl->fl_wait, |
|
list_empty(&new_fl->fl_blocked_member), |
|
break_time); |
|
|
|
percpu_down_read(&file_rwsem); |
|
spin_lock(&ctx->flc_lock); |
|
trace_break_lease_unblock(inode, new_fl); |
|
locks_delete_block(new_fl); |
|
if (error >= 0) { |
|
/* |
|
* Wait for the next conflicting lease that has not been |
|
* broken yet |
|
*/ |
|
if (error == 0) |
|
time_out_leases(inode, &dispose); |
|
if (any_leases_conflict(inode, new_fl)) |
|
goto restart; |
|
error = 0; |
|
} |
|
out: |
|
spin_unlock(&ctx->flc_lock); |
|
percpu_up_read(&file_rwsem); |
|
locks_dispose_list(&dispose); |
|
free_lock: |
|
locks_free_lock(new_fl); |
|
return error; |
|
} |
|
EXPORT_SYMBOL(__break_lease); |
|
|
|
/** |
|
* lease_get_mtime - update modified time of an inode with exclusive lease |
|
* @inode: the inode |
|
* @time: pointer to a timespec which contains the last modified time |
|
* |
|
* This is to force NFS clients to flush their caches for files with |
|
* exclusive leases. The justification is that if someone has an |
|
* exclusive lease, then they could be modifying it. |
|
*/ |
|
void lease_get_mtime(struct inode *inode, struct timespec64 *time) |
|
{ |
|
bool has_lease = false; |
|
struct file_lock_context *ctx; |
|
struct file_lock *fl; |
|
|
|
ctx = smp_load_acquire(&inode->i_flctx); |
|
if (ctx && !list_empty_careful(&ctx->flc_lease)) { |
|
spin_lock(&ctx->flc_lock); |
|
fl = list_first_entry_or_null(&ctx->flc_lease, |
|
struct file_lock, fl_list); |
|
if (fl && (fl->fl_type == F_WRLCK)) |
|
has_lease = true; |
|
spin_unlock(&ctx->flc_lock); |
|
} |
|
|
|
if (has_lease) |
|
*time = current_time(inode); |
|
} |
|
EXPORT_SYMBOL(lease_get_mtime); |
|
|
|
/** |
|
* fcntl_getlease - Enquire what lease is currently active |
|
* @filp: the file |
|
* |
|
* The value returned by this function will be one of |
|
* (if no lease break is pending): |
|
* |
|
* %F_RDLCK to indicate a shared lease is held. |
|
* |
|
* %F_WRLCK to indicate an exclusive lease is held. |
|
* |
|
* %F_UNLCK to indicate no lease is held. |
|
* |
|
* (if a lease break is pending): |
|
* |
|
* %F_RDLCK to indicate an exclusive lease needs to be |
|
* changed to a shared lease (or removed). |
|
* |
|
* %F_UNLCK to indicate the lease needs to be removed. |
|
* |
|
* XXX: sfr & willy disagree over whether F_INPROGRESS |
|
* should be returned to userspace. |
|
*/ |
|
int fcntl_getlease(struct file *filp) |
|
{ |
|
struct file_lock *fl; |
|
struct inode *inode = locks_inode(filp); |
|
struct file_lock_context *ctx; |
|
int type = F_UNLCK; |
|
LIST_HEAD(dispose); |
|
|
|
ctx = smp_load_acquire(&inode->i_flctx); |
|
if (ctx && !list_empty_careful(&ctx->flc_lease)) { |
|
percpu_down_read(&file_rwsem); |
|
spin_lock(&ctx->flc_lock); |
|
time_out_leases(inode, &dispose); |
|
list_for_each_entry(fl, &ctx->flc_lease, fl_list) { |
|
if (fl->fl_file != filp) |
|
continue; |
|
type = target_leasetype(fl); |
|
break; |
|
} |
|
spin_unlock(&ctx->flc_lock); |
|
percpu_up_read(&file_rwsem); |
|
|
|
locks_dispose_list(&dispose); |
|
} |
|
return type; |
|
} |
|
|
|
/** |
|
* check_conflicting_open - see if the given file points to an inode that has |
|
* an existing open that would conflict with the |
|
* desired lease. |
|
* @filp: file to check |
|
* @arg: type of lease that we're trying to acquire |
|
* @flags: current lock flags |
|
* |
|
* Check to see if there's an existing open fd on this file that would |
|
* conflict with the lease we're trying to set. |
|
*/ |
|
static int |
|
check_conflicting_open(struct file *filp, const long arg, int flags) |
|
{ |
|
struct inode *inode = locks_inode(filp); |
|
int self_wcount = 0, self_rcount = 0; |
|
|
|
if (flags & FL_LAYOUT) |
|
return 0; |
|
if (flags & FL_DELEG) |
|
/* We leave these checks to the caller */ |
|
return 0; |
|
|
|
if (arg == F_RDLCK) |
|
return inode_is_open_for_write(inode) ? -EAGAIN : 0; |
|
else if (arg != F_WRLCK) |
|
return 0; |
|
|
|
/* |
|
* Make sure that only read/write count is from lease requestor. |
|
* Note that this will result in denying write leases when i_writecount |
|
* is negative, which is what we want. (We shouldn't grant write leases |
|
* on files open for execution.) |
|
*/ |
|
if (filp->f_mode & FMODE_WRITE) |
|
self_wcount = 1; |
|
else if (filp->f_mode & FMODE_READ) |
|
self_rcount = 1; |
|
|
|
if (atomic_read(&inode->i_writecount) != self_wcount || |
|
atomic_read(&inode->i_readcount) != self_rcount) |
|
return -EAGAIN; |
|
|
|
return 0; |
|
} |
|
|
|
static int |
|
generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **priv) |
|
{ |
|
struct file_lock *fl, *my_fl = NULL, *lease; |
|
struct inode *inode = locks_inode(filp); |
|
struct file_lock_context *ctx; |
|
bool is_deleg = (*flp)->fl_flags & FL_DELEG; |
|
int error; |
|
LIST_HEAD(dispose); |
|
|
|
lease = *flp; |
|
trace_generic_add_lease(inode, lease); |
|
|
|
/* Note that arg is never F_UNLCK here */ |
|
ctx = locks_get_lock_context(inode, arg); |
|
if (!ctx) |
|
return -ENOMEM; |
|
|
|
/* |
|
* In the delegation case we need mutual exclusion with |
|
* a number of operations that take the i_mutex. We trylock |
|
* because delegations are an optional optimization, and if |
|
* there's some chance of a conflict--we'd rather not |
|
* bother, maybe that's a sign this just isn't a good file to |
|
* hand out a delegation on. |
|
*/ |
|
if (is_deleg && !inode_trylock(inode)) |
|
return -EAGAIN; |
|
|
|
if (is_deleg && arg == F_WRLCK) { |
|
/* Write delegations are not currently supported: */ |
|
inode_unlock(inode); |
|
WARN_ON_ONCE(1); |
|
return -EINVAL; |
|
} |
|
|
|
percpu_down_read(&file_rwsem); |
|
spin_lock(&ctx->flc_lock); |
|
time_out_leases(inode, &dispose); |
|
error = check_conflicting_open(filp, arg, lease->fl_flags); |
|
if (error) |
|
goto out; |
|
|
|
/* |
|
* At this point, we know that if there is an exclusive |
|
* lease on this file, then we hold it on this filp |
|
* (otherwise our open of this file would have blocked). |
|
* And if we are trying to acquire an exclusive lease, |
|
* then the file is not open by anyone (including us) |
|
* except for this filp. |
|
*/ |
|
error = -EAGAIN; |
|
list_for_each_entry(fl, &ctx->flc_lease, fl_list) { |
|
if (fl->fl_file == filp && |
|
fl->fl_owner == lease->fl_owner) { |
|
my_fl = fl; |
|
continue; |
|
} |
|
|
|
/* |
|
* No exclusive leases if someone else has a lease on |
|
* this file: |
|
*/ |
|
if (arg == F_WRLCK) |
|
goto out; |
|
/* |
|
* Modifying our existing lease is OK, but no getting a |
|
* new lease if someone else is opening for write: |
|
*/ |
|
if (fl->fl_flags & FL_UNLOCK_PENDING) |
|
goto out; |
|
} |
|
|
|
if (my_fl != NULL) { |
|
lease = my_fl; |
|
error = lease->fl_lmops->lm_change(lease, arg, &dispose); |
|
if (error) |
|
goto out; |
|
goto out_setup; |
|
} |
|
|
|
error = -EINVAL; |
|
if (!leases_enable) |
|
goto out; |
|
|
|
locks_insert_lock_ctx(lease, &ctx->flc_lease); |
|
/* |
|
* The check in break_lease() is lockless. It's possible for another |
|
* open to race in after we did the earlier check for a conflicting |
|
* open but before the lease was inserted. Check again for a |
|
* conflicting open and cancel the lease if there is one. |
|
* |
|
* We also add a barrier here to ensure that the insertion of the lock |
|
* precedes these checks. |
|
*/ |
|
smp_mb(); |
|
error = check_conflicting_open(filp, arg, lease->fl_flags); |
|
if (error) { |
|
locks_unlink_lock_ctx(lease); |
|
goto out; |
|
} |
|
|
|
out_setup: |
|
if (lease->fl_lmops->lm_setup) |
|
lease->fl_lmops->lm_setup(lease, priv); |
|
out: |
|
spin_unlock(&ctx->flc_lock); |
|
percpu_up_read(&file_rwsem); |
|
locks_dispose_list(&dispose); |
|
if (is_deleg) |
|
inode_unlock(inode); |
|
if (!error && !my_fl) |
|
*flp = NULL; |
|
return error; |
|
} |
|
|
|
static int generic_delete_lease(struct file *filp, void *owner) |
|
{ |
|
int error = -EAGAIN; |
|
struct file_lock *fl, *victim = NULL; |
|
struct inode *inode = locks_inode(filp); |
|
struct file_lock_context *ctx; |
|
LIST_HEAD(dispose); |
|
|
|
ctx = smp_load_acquire(&inode->i_flctx); |
|
if (!ctx) { |
|
trace_generic_delete_lease(inode, NULL); |
|
return error; |
|
} |
|
|
|
percpu_down_read(&file_rwsem); |
|
spin_lock(&ctx->flc_lock); |
|
list_for_each_entry(fl, &ctx->flc_lease, fl_list) { |
|
if (fl->fl_file == filp && |
|
fl->fl_owner == owner) { |
|
victim = fl; |
|
break; |
|
} |
|
} |
|
trace_generic_delete_lease(inode, victim); |
|
if (victim) |
|
error = fl->fl_lmops->lm_change(victim, F_UNLCK, &dispose); |
|
spin_unlock(&ctx->flc_lock); |
|
percpu_up_read(&file_rwsem); |
|
locks_dispose_list(&dispose); |
|
return error; |
|
} |
|
|
|
/** |
|
* generic_setlease - sets a lease on an open file |
|
* @filp: file pointer |
|
* @arg: type of lease to obtain |
|
* @flp: input - file_lock to use, output - file_lock inserted |
|
* @priv: private data for lm_setup (may be NULL if lm_setup |
|
* doesn't require it) |
|
* |
|
* The (input) flp->fl_lmops->lm_break function is required |
|
* by break_lease(). |
|
*/ |
|
int generic_setlease(struct file *filp, long arg, struct file_lock **flp, |
|
void **priv) |
|
{ |
|
struct inode *inode = locks_inode(filp); |
|
int error; |
|
|
|
if ((!uid_eq(current_fsuid(), inode->i_uid)) && !capable(CAP_LEASE)) |
|
return -EACCES; |
|
if (!S_ISREG(inode->i_mode)) |
|
return -EINVAL; |
|
error = security_file_lock(filp, arg); |
|
if (error) |
|
return error; |
|
|
|
switch (arg) { |
|
case F_UNLCK: |
|
return generic_delete_lease(filp, *priv); |
|
case F_RDLCK: |
|
case F_WRLCK: |
|
if (!(*flp)->fl_lmops->lm_break) { |
|
WARN_ON_ONCE(1); |
|
return -ENOLCK; |
|
} |
|
|
|
return generic_add_lease(filp, arg, flp, priv); |
|
default: |
|
return -EINVAL; |
|
} |
|
} |
|
EXPORT_SYMBOL(generic_setlease); |
|
|
|
#if IS_ENABLED(CONFIG_SRCU) |
|
/* |
|
* Kernel subsystems can register to be notified on any attempt to set |
|
* a new lease with the lease_notifier_chain. This is used by (e.g.) nfsd |
|
* to close files that it may have cached when there is an attempt to set a |
|
* conflicting lease. |
|
*/ |
|
static struct srcu_notifier_head lease_notifier_chain; |
|
|
|
static inline void |
|
lease_notifier_chain_init(void) |
|
{ |
|
srcu_init_notifier_head(&lease_notifier_chain); |
|
} |
|
|
|
static inline void |
|
setlease_notifier(long arg, struct file_lock *lease) |
|
{ |
|
if (arg != F_UNLCK) |
|
srcu_notifier_call_chain(&lease_notifier_chain, arg, lease); |
|
} |
|
|
|
int lease_register_notifier(struct notifier_block *nb) |
|
{ |
|
return srcu_notifier_chain_register(&lease_notifier_chain, nb); |
|
} |
|
EXPORT_SYMBOL_GPL(lease_register_notifier); |
|
|
|
void lease_unregister_notifier(struct notifier_block *nb) |
|
{ |
|
srcu_notifier_chain_unregister(&lease_notifier_chain, nb); |
|
} |
|
EXPORT_SYMBOL_GPL(lease_unregister_notifier); |
|
|
|
#else /* !IS_ENABLED(CONFIG_SRCU) */ |
|
static inline void |
|
lease_notifier_chain_init(void) |
|
{ |
|
} |
|
|
|
static inline void |
|
setlease_notifier(long arg, struct file_lock *lease) |
|
{ |
|
} |
|
|
|
int lease_register_notifier(struct notifier_block *nb) |
|
{ |
|
return 0; |
|
} |
|
EXPORT_SYMBOL_GPL(lease_register_notifier); |
|
|
|
void lease_unregister_notifier(struct notifier_block *nb) |
|
{ |
|
} |
|
EXPORT_SYMBOL_GPL(lease_unregister_notifier); |
|
|
|
#endif /* IS_ENABLED(CONFIG_SRCU) */ |
|
|
|
/** |
|
* vfs_setlease - sets a lease on an open file |
|
* @filp: file pointer |
|
* @arg: type of lease to obtain |
|
* @lease: file_lock to use when adding a lease |
|
* @priv: private info for lm_setup when adding a lease (may be |
|
* NULL if lm_setup doesn't require it) |
|
* |
|
* Call this to establish a lease on the file. The "lease" argument is not |
|
* used for F_UNLCK requests and may be NULL. For commands that set or alter |
|
* an existing lease, the ``(*lease)->fl_lmops->lm_break`` operation must be |
|
* set; if not, this function will return -ENOLCK (and generate a scary-looking |
|
* stack trace). |
|
* |
|
* The "priv" pointer is passed directly to the lm_setup function as-is. It |
|
* may be NULL if the lm_setup operation doesn't require it. |
|
*/ |
|
int |
|
vfs_setlease(struct file *filp, long arg, struct file_lock **lease, void **priv) |
|
{ |
|
if (lease) |
|
setlease_notifier(arg, *lease); |
|
if (filp->f_op->setlease) |
|
return filp->f_op->setlease(filp, arg, lease, priv); |
|
else |
|
return generic_setlease(filp, arg, lease, priv); |
|
} |
|
EXPORT_SYMBOL_GPL(vfs_setlease); |
|
|
|
static int do_fcntl_add_lease(unsigned int fd, struct file *filp, long arg) |
|
{ |
|
struct file_lock *fl; |
|
struct fasync_struct *new; |
|
int error; |
|
|
|
fl = lease_alloc(filp, arg); |
|
if (IS_ERR(fl)) |
|
return PTR_ERR(fl); |
|
|
|
new = fasync_alloc(); |
|
if (!new) { |
|
locks_free_lock(fl); |
|
return -ENOMEM; |
|
} |
|
new->fa_fd = fd; |
|
|
|
error = vfs_setlease(filp, arg, &fl, (void **)&new); |
|
if (fl) |
|
locks_free_lock(fl); |
|
if (new) |
|
fasync_free(new); |
|
return error; |
|
} |
|
|
|
/** |
|
* fcntl_setlease - sets a lease on an open file |
|
* @fd: open file descriptor |
|
* @filp: file pointer |
|
* @arg: type of lease to obtain |
|
* |
|
* Call this fcntl to establish a lease on the file. |
|
* Note that you also need to call %F_SETSIG to |
|
* receive a signal when the lease is broken. |
|
*/ |
|
int fcntl_setlease(unsigned int fd, struct file *filp, long arg) |
|
{ |
|
if (arg == F_UNLCK) |
|
return vfs_setlease(filp, F_UNLCK, NULL, (void **)&filp); |
|
return do_fcntl_add_lease(fd, filp, arg); |
|
} |
|
|
|
/** |
|
* flock_lock_inode_wait - Apply a FLOCK-style lock to a file |
|
* @inode: inode of the file to apply to |
|
* @fl: The lock to be applied |
|
* |
|
* Apply a FLOCK style lock request to an inode. |
|
*/ |
|
static int flock_lock_inode_wait(struct inode *inode, struct file_lock *fl) |
|
{ |
|
int error; |
|
might_sleep(); |
|
for (;;) { |
|
error = flock_lock_inode(inode, fl); |
|
if (error != FILE_LOCK_DEFERRED) |
|
break; |
|
error = wait_event_interruptible(fl->fl_wait, |
|
list_empty(&fl->fl_blocked_member)); |
|
if (error) |
|
break; |
|
} |
|
locks_delete_block(fl); |
|
return error; |
|
} |
|
|
|
/** |
|
* locks_lock_inode_wait - Apply a lock to an inode |
|
* @inode: inode of the file to apply to |
|
* @fl: The lock to be applied |
|
* |
|
* Apply a POSIX or FLOCK style lock request to an inode. |
|
*/ |
|
int locks_lock_inode_wait(struct inode *inode, struct file_lock *fl) |
|
{ |
|
int res = 0; |
|
switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) { |
|
case FL_POSIX: |
|
res = posix_lock_inode_wait(inode, fl); |
|
break; |
|
case FL_FLOCK: |
|
res = flock_lock_inode_wait(inode, fl); |
|
break; |
|
default: |
|
BUG(); |
|
} |
|
return res; |
|
} |
|
EXPORT_SYMBOL(locks_lock_inode_wait); |
|
|
|
/** |
|
* sys_flock: - flock() system call. |
|
* @fd: the file descriptor to lock. |
|
* @cmd: the type of lock to apply. |
|
* |
|
* Apply a %FL_FLOCK style lock to an open file descriptor. |
|
* The @cmd can be one of: |
|
* |
|
* - %LOCK_SH -- a shared lock. |
|
* - %LOCK_EX -- an exclusive lock. |
|
* - %LOCK_UN -- remove an existing lock. |
|
* - %LOCK_MAND -- a 'mandatory' flock. (DEPRECATED) |
|
* |
|
* %LOCK_MAND support has been removed from the kernel. |
|
*/ |
|
SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd) |
|
{ |
|
struct fd f = fdget(fd); |
|
struct file_lock *lock; |
|
int can_sleep, unlock; |
|
int error; |
|
|
|
error = -EBADF; |
|
if (!f.file) |
|
goto out; |
|
|
|
can_sleep = !(cmd & LOCK_NB); |
|
cmd &= ~LOCK_NB; |
|
unlock = (cmd == LOCK_UN); |
|
|
|
if (!unlock && !(f.file->f_mode & (FMODE_READ|FMODE_WRITE))) |
|
goto out_putf; |
|
|
|
/* |
|
* LOCK_MAND locks were broken for a long time in that they never |
|
* conflicted with one another and didn't prevent any sort of open, |
|
* read or write activity. |
|
* |
|
* Just ignore these requests now, to preserve legacy behavior, but |
|
* throw a warning to let people know that they don't actually work. |
|
*/ |
|
if (cmd & LOCK_MAND) { |
|
pr_warn_once("Attempt to set a LOCK_MAND lock via flock(2). This support has been removed and the request ignored.\n"); |
|
error = 0; |
|
goto out_putf; |
|
} |
|
|
|
lock = flock_make_lock(f.file, cmd, NULL); |
|
if (IS_ERR(lock)) { |
|
error = PTR_ERR(lock); |
|
goto out_putf; |
|
} |
|
|
|
if (can_sleep) |
|
lock->fl_flags |= FL_SLEEP; |
|
|
|
error = security_file_lock(f.file, lock->fl_type); |
|
if (error) |
|
goto out_free; |
|
|
|
if (f.file->f_op->flock) |
|
error = f.file->f_op->flock(f.file, |
|
(can_sleep) ? F_SETLKW : F_SETLK, |
|
lock); |
|
else |
|
error = locks_lock_file_wait(f.file, lock); |
|
|
|
out_free: |
|
locks_free_lock(lock); |
|
|
|
out_putf: |
|
fdput(f); |
|
out: |
|
return error; |
|
} |
|
|
|
/** |
|
* vfs_test_lock - test file byte range lock |
|
* @filp: The file to test lock for |
|
* @fl: The lock to test; also used to hold result |
|
* |
|
* Returns -ERRNO on failure. Indicates presence of conflicting lock by |
|
* setting conf->fl_type to something other than F_UNLCK. |
|
*/ |
|
int vfs_test_lock(struct file *filp, struct file_lock *fl) |
|
{ |
|
if (filp->f_op->lock) |
|
return filp->f_op->lock(filp, F_GETLK, fl); |
|
posix_test_lock(filp, fl); |
|
return 0; |
|
} |
|
EXPORT_SYMBOL_GPL(vfs_test_lock); |
|
|
|
/** |
|
* locks_translate_pid - translate a file_lock's fl_pid number into a namespace |
|
* @fl: The file_lock who's fl_pid should be translated |
|
* @ns: The namespace into which the pid should be translated |
|
* |
|
* Used to tranlate a fl_pid into a namespace virtual pid number |
|
*/ |
|
static pid_t locks_translate_pid(struct file_lock *fl, struct pid_namespace *ns) |
|
{ |
|
pid_t vnr; |
|
struct pid *pid; |
|
|
|
if (IS_OFDLCK(fl)) |
|
return -1; |
|
if (IS_REMOTELCK(fl)) |
|
return fl->fl_pid; |
|
/* |
|
* If the flock owner process is dead and its pid has been already |
|
* freed, the translation below won't work, but we still want to show |
|
* flock owner pid number in init pidns. |
|
*/ |
|
if (ns == &init_pid_ns) |
|
return (pid_t)fl->fl_pid; |
|
|
|
rcu_read_lock(); |
|
pid = find_pid_ns(fl->fl_pid, &init_pid_ns); |
|
vnr = pid_nr_ns(pid, ns); |
|
rcu_read_unlock(); |
|
return vnr; |
|
} |
|
|
|
static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl) |
|
{ |
|
flock->l_pid = locks_translate_pid(fl, task_active_pid_ns(current)); |
|
#if BITS_PER_LONG == 32 |
|
/* |
|
* Make sure we can represent the posix lock via |
|
* legacy 32bit flock. |
|
*/ |
|
if (fl->fl_start > OFFT_OFFSET_MAX) |
|
return -EOVERFLOW; |
|
if (fl->fl_end != OFFSET_MAX && fl->fl_end > OFFT_OFFSET_MAX) |
|
return -EOVERFLOW; |
|
#endif |
|
flock->l_start = fl->fl_start; |
|
flock->l_len = fl->fl_end == OFFSET_MAX ? 0 : |
|
fl->fl_end - fl->fl_start + 1; |
|
flock->l_whence = 0; |
|
flock->l_type = fl->fl_type; |
|
return 0; |
|
} |
|
|
|
#if BITS_PER_LONG == 32 |
|
static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl) |
|
{ |
|
flock->l_pid = locks_translate_pid(fl, task_active_pid_ns(current)); |
|
flock->l_start = fl->fl_start; |
|
flock->l_len = fl->fl_end == OFFSET_MAX ? 0 : |
|
fl->fl_end - fl->fl_start + 1; |
|
flock->l_whence = 0; |
|
flock->l_type = fl->fl_type; |
|
} |
|
#endif |
|
|
|
/* Report the first existing lock that would conflict with l. |
|
* This implements the F_GETLK command of fcntl(). |
|
*/ |
|
int fcntl_getlk(struct file *filp, unsigned int cmd, struct flock *flock) |
|
{ |
|
struct file_lock *fl; |
|
int error; |
|
|
|
fl = locks_alloc_lock(); |
|
if (fl == NULL) |
|
return -ENOMEM; |
|
error = -EINVAL; |
|
if (flock->l_type != F_RDLCK && flock->l_type != F_WRLCK) |
|
goto out; |
|
|
|
error = flock_to_posix_lock(filp, fl, flock); |
|
if (error) |
|
goto out; |
|
|
|
if (cmd == F_OFD_GETLK) { |
|
error = -EINVAL; |
|
if (flock->l_pid != 0) |
|
goto out; |
|
|
|
fl->fl_flags |= FL_OFDLCK; |
|
fl->fl_owner = filp; |
|
} |
|
|
|
error = vfs_test_lock(filp, fl); |
|
if (error) |
|
goto out; |
|
|
|
flock->l_type = fl->fl_type; |
|
if (fl->fl_type != F_UNLCK) { |
|
error = posix_lock_to_flock(flock, fl); |
|
if (error) |
|
goto out; |
|
} |
|
out: |
|
locks_free_lock(fl); |
|
return error; |
|
} |
|
|
|
/** |
|
* vfs_lock_file - file byte range lock |
|
* @filp: The file to apply the lock to |
|
* @cmd: type of locking operation (F_SETLK, F_GETLK, etc.) |
|
* @fl: The lock to be applied |
|
* @conf: Place to return a copy of the conflicting lock, if found. |
|
* |
|
* A caller that doesn't care about the conflicting lock may pass NULL |
|
* as the final argument. |
|
* |
|
* If the filesystem defines a private ->lock() method, then @conf will |
|
* be left unchanged; so a caller that cares should initialize it to |
|
* some acceptable default. |
|
* |
|
* To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX |
|
* locks, the ->lock() interface may return asynchronously, before the lock has |
|
* been granted or denied by the underlying filesystem, if (and only if) |
|
* lm_grant is set. Callers expecting ->lock() to return asynchronously |
|
* will only use F_SETLK, not F_SETLKW; they will set FL_SLEEP if (and only if) |
|
* the request is for a blocking lock. When ->lock() does return asynchronously, |
|
* it must return FILE_LOCK_DEFERRED, and call ->lm_grant() when the lock |
|
* request completes. |
|
* If the request is for non-blocking lock the file system should return |
|
* FILE_LOCK_DEFERRED then try to get the lock and call the callback routine |
|
* with the result. If the request timed out the callback routine will return a |
|
* nonzero return code and the file system should release the lock. The file |
|
* system is also responsible to keep a corresponding posix lock when it |
|
* grants a lock so the VFS can find out which locks are locally held and do |
|
* the correct lock cleanup when required. |
|
* The underlying filesystem must not drop the kernel lock or call |
|
* ->lm_grant() before returning to the caller with a FILE_LOCK_DEFERRED |
|
* return code. |
|
*/ |
|
int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf) |
|
{ |
|
if (filp->f_op->lock) |
|
return filp->f_op->lock(filp, cmd, fl); |
|
else |
|
return posix_lock_file(filp, fl, conf); |
|
} |
|
EXPORT_SYMBOL_GPL(vfs_lock_file); |
|
|
|
static int do_lock_file_wait(struct file *filp, unsigned int cmd, |
|
struct file_lock *fl) |
|
{ |
|
int error; |
|
|
|
error = security_file_lock(filp, fl->fl_type); |
|
if (error) |
|
return error; |
|
|
|
for (;;) { |
|
error = vfs_lock_file(filp, cmd, fl, NULL); |
|
if (error != FILE_LOCK_DEFERRED) |
|
break; |
|
error = wait_event_interruptible(fl->fl_wait, |
|
list_empty(&fl->fl_blocked_member)); |
|
if (error) |
|
break; |
|
} |
|
locks_delete_block(fl); |
|
|
|
return error; |
|
} |
|
|
|
/* Ensure that fl->fl_file has compatible f_mode for F_SETLK calls */ |
|
static int |
|
check_fmode_for_setlk(struct file_lock *fl) |
|
{ |
|
switch (fl->fl_type) { |
|
case F_RDLCK: |
|
if (!(fl->fl_file->f_mode & FMODE_READ)) |
|
return -EBADF; |
|
break; |
|
case F_WRLCK: |
|
if (!(fl->fl_file->f_mode & FMODE_WRITE)) |
|
return -EBADF; |
|
} |
|
return 0; |
|
} |
|
|
|
/* Apply the lock described by l to an open file descriptor. |
|
* This implements both the F_SETLK and F_SETLKW commands of fcntl(). |
|
*/ |
|
int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd, |
|
struct flock *flock) |
|
{ |
|
struct file_lock *file_lock = locks_alloc_lock(); |
|
struct inode *inode = locks_inode(filp); |
|
struct file *f; |
|
int error; |
|
|
|
if (file_lock == NULL) |
|
return -ENOLCK; |
|
|
|
error = flock_to_posix_lock(filp, file_lock, flock); |
|
if (error) |
|
goto out; |
|
|
|
error = check_fmode_for_setlk(file_lock); |
|
if (error) |
|
goto out; |
|
|
|
/* |
|
* If the cmd is requesting file-private locks, then set the |
|
* FL_OFDLCK flag and override the owner. |
|
*/ |
|
switch (cmd) { |
|
case F_OFD_SETLK: |
|
error = -EINVAL; |
|
if (flock->l_pid != 0) |
|
goto out; |
|
|
|
cmd = F_SETLK; |
|
file_lock->fl_flags |= FL_OFDLCK; |
|
file_lock->fl_owner = filp; |
|
break; |
|
case F_OFD_SETLKW: |
|
error = -EINVAL; |
|
if (flock->l_pid != 0) |
|
goto out; |
|
|
|
cmd = F_SETLKW; |
|
file_lock->fl_flags |= FL_OFDLCK; |
|
file_lock->fl_owner = filp; |
|
fallthrough; |
|
case F_SETLKW: |
|
file_lock->fl_flags |= FL_SLEEP; |
|
} |
|
|
|
error = do_lock_file_wait(filp, cmd, file_lock); |
|
|
|
/* |
|
* Attempt to detect a close/fcntl race and recover by releasing the |
|
* lock that was just acquired. There is no need to do that when we're |
|
* unlocking though, or for OFD locks. |
|
*/ |
|
if (!error && file_lock->fl_type != F_UNLCK && |
|
!(file_lock->fl_flags & FL_OFDLCK)) { |
|
struct files_struct *files = current->files; |
|
/* |
|
* We need that spin_lock here - it prevents reordering between |
|
* update of i_flctx->flc_posix and check for it done in |
|
* close(). rcu_read_lock() wouldn't do. |
|
*/ |
|
spin_lock(&files->file_lock); |
|
f = files_lookup_fd_locked(files, fd); |
|
spin_unlock(&files->file_lock); |
|
if (f != filp) { |
|
file_lock->fl_type = F_UNLCK; |
|
error = do_lock_file_wait(filp, cmd, file_lock); |
|
WARN_ON_ONCE(error); |
|
error = -EBADF; |
|
} |
|
} |
|
out: |
|
trace_fcntl_setlk(inode, file_lock, error); |
|
locks_free_lock(file_lock); |
|
return error; |
|
} |
|
|
|
#if BITS_PER_LONG == 32 |
|
/* Report the first existing lock that would conflict with l. |
|
* This implements the F_GETLK command of fcntl(). |
|
*/ |
|
int fcntl_getlk64(struct file *filp, unsigned int cmd, struct flock64 *flock) |
|
{ |
|
struct file_lock *fl; |
|
int error; |
|
|
|
fl = locks_alloc_lock(); |
|
if (fl == NULL) |
|
return -ENOMEM; |
|
|
|
error = -EINVAL; |
|
if (flock->l_type != F_RDLCK && flock->l_type != F_WRLCK) |
|
goto out; |
|
|
|
error = flock64_to_posix_lock(filp, fl, flock); |
|
if (error) |
|
goto out; |
|
|
|
if (cmd == F_OFD_GETLK) { |
|
error = -EINVAL; |
|
if (flock->l_pid != 0) |
|
goto out; |
|
|
|
cmd = F_GETLK64; |
|
fl->fl_flags |= FL_OFDLCK; |
|
fl->fl_owner = filp; |
|
} |
|
|
|
error = vfs_test_lock(filp, fl); |
|
if (error) |
|
goto out; |
|
|
|
flock->l_type = fl->fl_type; |
|
if (fl->fl_type != F_UNLCK) |
|
posix_lock_to_flock64(flock, fl); |
|
|
|
out: |
|
locks_free_lock(fl); |
|
return error; |
|
} |
|
|
|
/* Apply the lock described by l to an open file descriptor. |
|
* This implements both the F_SETLK and F_SETLKW commands of fcntl(). |
|
*/ |
|
int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd, |
|
struct flock64 *flock) |
|
{ |
|
struct file_lock *file_lock = locks_alloc_lock(); |
|
struct file *f; |
|
int error; |
|
|
|
if (file_lock == NULL) |
|
return -ENOLCK; |
|
|
|
error = flock64_to_posix_lock(filp, file_lock, flock); |
|
if (error) |
|
goto out; |
|
|
|
error = check_fmode_for_setlk(file_lock); |
|
if (error) |
|
goto out; |
|
|
|
/* |
|
* If the cmd is requesting file-private locks, then set the |
|
* FL_OFDLCK flag and override the owner. |
|
*/ |
|
switch (cmd) { |
|
case F_OFD_SETLK: |
|
error = -EINVAL; |
|
if (flock->l_pid != 0) |
|
goto out; |
|
|
|
cmd = F_SETLK64; |
|
file_lock->fl_flags |= FL_OFDLCK; |
|
file_lock->fl_owner = filp; |
|
break; |
|
case F_OFD_SETLKW: |
|
error = -EINVAL; |
|
if (flock->l_pid != 0) |
|
goto out; |
|
|
|
cmd = F_SETLKW64; |
|
file_lock->fl_flags |= FL_OFDLCK; |
|
file_lock->fl_owner = filp; |
|
fallthrough; |
|
case F_SETLKW64: |
|
file_lock->fl_flags |= FL_SLEEP; |
|
} |
|
|
|
error = do_lock_file_wait(filp, cmd, file_lock); |
|
|
|
/* |
|
* Attempt to detect a close/fcntl race and recover by releasing the |
|
* lock that was just acquired. There is no need to do that when we're |
|
* unlocking though, or for OFD locks. |
|
*/ |
|
if (!error && file_lock->fl_type != F_UNLCK && |
|
!(file_lock->fl_flags & FL_OFDLCK)) { |
|
struct files_struct *files = current->files; |
|
/* |
|
* We need that spin_lock here - it prevents reordering between |
|
* update of i_flctx->flc_posix and check for it done in |
|
* close(). rcu_read_lock() wouldn't do. |
|
*/ |
|
spin_lock(&files->file_lock); |
|
f = files_lookup_fd_locked(files, fd); |
|
spin_unlock(&files->file_lock); |
|
if (f != filp) { |
|
file_lock->fl_type = F_UNLCK; |
|
error = do_lock_file_wait(filp, cmd, file_lock); |
|
WARN_ON_ONCE(error); |
|
error = -EBADF; |
|
} |
|
} |
|
out: |
|
locks_free_lock(file_lock); |
|
return error; |
|
} |
|
#endif /* BITS_PER_LONG == 32 */ |
|
|
|
/* |
|
* This function is called when the file is being removed |
|
* from the task's fd array. POSIX locks belonging to this task |
|
* are deleted at this time. |
|
*/ |
|
void locks_remove_posix(struct file *filp, fl_owner_t owner) |
|
{ |
|
int error; |
|
struct inode *inode = locks_inode(filp); |
|
struct file_lock lock; |
|
struct file_lock_context *ctx; |
|
|
|
/* |
|
* If there are no locks held on this file, we don't need to call |
|
* posix_lock_file(). Another process could be setting a lock on this |
|
* file at the same time, but we wouldn't remove that lock anyway. |
|
*/ |
|
ctx = smp_load_acquire(&inode->i_flctx); |
|
if (!ctx || list_empty(&ctx->flc_posix)) |
|
return; |
|
|
|
locks_init_lock(&lock); |
|
lock.fl_type = F_UNLCK; |
|
lock.fl_flags = FL_POSIX | FL_CLOSE; |
|
lock.fl_start = 0; |
|
lock.fl_end = OFFSET_MAX; |
|
lock.fl_owner = owner; |
|
lock.fl_pid = current->tgid; |
|
lock.fl_file = filp; |
|
lock.fl_ops = NULL; |
|
lock.fl_lmops = NULL; |
|
|
|
error = vfs_lock_file(filp, F_SETLK, &lock, NULL); |
|
|
|
if (lock.fl_ops && lock.fl_ops->fl_release_private) |
|
lock.fl_ops->fl_release_private(&lock); |
|
trace_locks_remove_posix(inode, &lock, error); |
|
} |
|
EXPORT_SYMBOL(locks_remove_posix); |
|
|
|
/* The i_flctx must be valid when calling into here */ |
|
static void |
|
locks_remove_flock(struct file *filp, struct file_lock_context *flctx) |
|
{ |
|
struct file_lock fl; |
|
struct inode *inode = locks_inode(filp); |
|
|
|
if (list_empty(&flctx->flc_flock)) |
|
return; |
|
|
|
flock_make_lock(filp, LOCK_UN, &fl); |
|
fl.fl_flags |= FL_CLOSE; |
|
|
|
if (filp->f_op->flock) |
|
filp->f_op->flock(filp, F_SETLKW, &fl); |
|
else |
|
flock_lock_inode(inode, &fl); |
|
|
|
if (fl.fl_ops && fl.fl_ops->fl_release_private) |
|
fl.fl_ops->fl_release_private(&fl); |
|
} |
|
|
|
/* The i_flctx must be valid when calling into here */ |
|
static void |
|
locks_remove_lease(struct file *filp, struct file_lock_context *ctx) |
|
{ |
|
struct file_lock *fl, *tmp; |
|
LIST_HEAD(dispose); |
|
|
|
if (list_empty(&ctx->flc_lease)) |
|
return; |
|
|
|
percpu_down_read(&file_rwsem); |
|
spin_lock(&ctx->flc_lock); |
|
list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list) |
|
if (filp == fl->fl_file) |
|
lease_modify(fl, F_UNLCK, &dispose); |
|
spin_unlock(&ctx->flc_lock); |
|
percpu_up_read(&file_rwsem); |
|
|
|
locks_dispose_list(&dispose); |
|
} |
|
|
|
/* |
|
* This function is called on the last close of an open file. |
|
*/ |
|
void locks_remove_file(struct file *filp) |
|
{ |
|
struct file_lock_context *ctx; |
|
|
|
ctx = smp_load_acquire(&locks_inode(filp)->i_flctx); |
|
if (!ctx) |
|
return; |
|
|
|
/* remove any OFD locks */ |
|
locks_remove_posix(filp, filp); |
|
|
|
/* remove flock locks */ |
|
locks_remove_flock(filp, ctx); |
|
|
|
/* remove any leases */ |
|
locks_remove_lease(filp, ctx); |
|
|
|
spin_lock(&ctx->flc_lock); |
|
locks_check_ctx_file_list(filp, &ctx->flc_posix, "POSIX"); |
|
locks_check_ctx_file_list(filp, &ctx->flc_flock, "FLOCK"); |
|
locks_check_ctx_file_list(filp, &ctx->flc_lease, "LEASE"); |
|
spin_unlock(&ctx->flc_lock); |
|
} |
|
|
|
/** |
|
* vfs_cancel_lock - file byte range unblock lock |
|
* @filp: The file to apply the unblock to |
|
* @fl: The lock to be unblocked |
|
* |
|
* Used by lock managers to cancel blocked requests |
|
*/ |
|
int vfs_cancel_lock(struct file *filp, struct file_lock *fl) |
|
{ |
|
if (filp->f_op->lock) |
|
return filp->f_op->lock(filp, F_CANCELLK, fl); |
|
return 0; |
|
} |
|
EXPORT_SYMBOL_GPL(vfs_cancel_lock); |
|
|
|
#ifdef CONFIG_PROC_FS |
|
#include <linux/proc_fs.h> |
|
#include <linux/seq_file.h> |
|
|
|
struct locks_iterator { |
|
int li_cpu; |
|
loff_t li_pos; |
|
}; |
|
|
|
static void lock_get_status(struct seq_file *f, struct file_lock *fl, |
|
loff_t id, char *pfx, int repeat) |
|
{ |
|
struct inode *inode = NULL; |
|
unsigned int fl_pid; |
|
struct pid_namespace *proc_pidns = proc_pid_ns(file_inode(f->file)->i_sb); |
|
int type; |
|
|
|
fl_pid = locks_translate_pid(fl, proc_pidns); |
|
/* |
|
* If lock owner is dead (and pid is freed) or not visible in current |
|
* pidns, zero is shown as a pid value. Check lock info from |
|
* init_pid_ns to get saved lock pid value. |
|
*/ |
|
|
|
if (fl->fl_file != NULL) |
|
inode = locks_inode(fl->fl_file); |
|
|
|
seq_printf(f, "%lld: ", id); |
|
|
|
if (repeat) |
|
seq_printf(f, "%*s", repeat - 1 + (int)strlen(pfx), pfx); |
|
|
|
if (IS_POSIX(fl)) { |
|
if (fl->fl_flags & FL_ACCESS) |
|
seq_puts(f, "ACCESS"); |
|
else if (IS_OFDLCK(fl)) |
|
seq_puts(f, "OFDLCK"); |
|
else |
|
seq_puts(f, "POSIX "); |
|
|
|
seq_printf(f, " %s ", |
|
(inode == NULL) ? "*NOINODE*" : "ADVISORY "); |
|
} else if (IS_FLOCK(fl)) { |
|
seq_puts(f, "FLOCK ADVISORY "); |
|
} else if (IS_LEASE(fl)) { |
|
if (fl->fl_flags & FL_DELEG) |
|
seq_puts(f, "DELEG "); |
|
else |
|
seq_puts(f, "LEASE "); |
|
|
|
if (lease_breaking(fl)) |
|
seq_puts(f, "BREAKING "); |
|
else if (fl->fl_file) |
|
seq_puts(f, "ACTIVE "); |
|
else |
|
seq_puts(f, "BREAKER "); |
|
} else { |
|
seq_puts(f, "UNKNOWN UNKNOWN "); |
|
} |
|
type = IS_LEASE(fl) ? target_leasetype(fl) : fl->fl_type; |
|
|
|
seq_printf(f, "%s ", (type == F_WRLCK) ? "WRITE" : |
|
(type == F_RDLCK) ? "READ" : "UNLCK"); |
|
if (inode) { |
|
/* userspace relies on this representation of dev_t */ |
|
seq_printf(f, "%d %02x:%02x:%lu ", fl_pid, |
|
MAJOR(inode->i_sb->s_dev), |
|
MINOR(inode->i_sb->s_dev), inode->i_ino); |
|
} else { |
|
seq_printf(f, "%d <none>:0 ", fl_pid); |
|
} |
|
if (IS_POSIX(fl)) { |
|
if (fl->fl_end == OFFSET_MAX) |
|
seq_printf(f, "%Ld EOF\n", fl->fl_start); |
|
else |
|
seq_printf(f, "%Ld %Ld\n", fl->fl_start, fl->fl_end); |
|
} else { |
|
seq_puts(f, "0 EOF\n"); |
|
} |
|
} |
|
|
|
static struct file_lock *get_next_blocked_member(struct file_lock *node) |
|
{ |
|
struct file_lock *tmp; |
|
|
|
/* NULL node or root node */ |
|
if (node == NULL || node->fl_blocker == NULL) |
|
return NULL; |
|
|
|
/* Next member in the linked list could be itself */ |
|
tmp = list_next_entry(node, fl_blocked_member); |
|
if (list_entry_is_head(tmp, &node->fl_blocker->fl_blocked_requests, fl_blocked_member) |
|
|| tmp == node) { |
|
return NULL; |
|
} |
|
|
|
return tmp; |
|
} |
|
|
|
static int locks_show(struct seq_file *f, void *v) |
|
{ |
|
struct locks_iterator *iter = f->private; |
|
struct file_lock *cur, *tmp; |
|
struct pid_namespace *proc_pidns = proc_pid_ns(file_inode(f->file)->i_sb); |
|
int level = 0; |
|
|
|
cur = hlist_entry(v, struct file_lock, fl_link); |
|
|
|
if (locks_translate_pid(cur, proc_pidns) == 0) |
|
return 0; |
|
|
|
/* View this crossed linked list as a binary tree, the first member of fl_blocked_requests |
|
* is the left child of current node, the next silibing in fl_blocked_member is the |
|
* right child, we can alse get the parent of current node from fl_blocker, so this |
|
* question becomes traversal of a binary tree |
|
*/ |
|
while (cur != NULL) { |
|
if (level) |
|
lock_get_status(f, cur, iter->li_pos, "-> ", level); |
|
else |
|
lock_get_status(f, cur, iter->li_pos, "", level); |
|
|
|
if (!list_empty(&cur->fl_blocked_requests)) { |
|
/* Turn left */ |
|
cur = list_first_entry_or_null(&cur->fl_blocked_requests, |
|
struct file_lock, fl_blocked_member); |
|
level++; |
|
} else { |
|
/* Turn right */ |
|
tmp = get_next_blocked_member(cur); |
|
/* Fall back to parent node */ |
|
while (tmp == NULL && cur->fl_blocker != NULL) { |
|
cur = cur->fl_blocker; |
|
level--; |
|
tmp = get_next_blocked_member(cur); |
|
} |
|
cur = tmp; |
|
} |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
static void __show_fd_locks(struct seq_file *f, |
|
struct list_head *head, int *id, |
|
struct file *filp, struct files_struct *files) |
|
{ |
|
struct file_lock *fl; |
|
|
|
list_for_each_entry(fl, head, fl_list) { |
|
|
|
if (filp != fl->fl_file) |
|
continue; |
|
if (fl->fl_owner != files && |
|
fl->fl_owner != filp) |
|
continue; |
|
|
|
(*id)++; |
|
seq_puts(f, "lock:\t"); |
|
lock_get_status(f, fl, *id, "", 0); |
|
} |
|
} |
|
|
|
void show_fd_locks(struct seq_file *f, |
|
struct file *filp, struct files_struct *files) |
|
{ |
|
struct inode *inode = locks_inode(filp); |
|
struct file_lock_context *ctx; |
|
int id = 0; |
|
|
|
ctx = smp_load_acquire(&inode->i_flctx); |
|
if (!ctx) |
|
return; |
|
|
|
spin_lock(&ctx->flc_lock); |
|
__show_fd_locks(f, &ctx->flc_flock, &id, filp, files); |
|
__show_fd_locks(f, &ctx->flc_posix, &id, filp, files); |
|
__show_fd_locks(f, &ctx->flc_lease, &id, filp, files); |
|
spin_unlock(&ctx->flc_lock); |
|
} |
|
|
|
static void *locks_start(struct seq_file *f, loff_t *pos) |
|
__acquires(&blocked_lock_lock) |
|
{ |
|
struct locks_iterator *iter = f->private; |
|
|
|
iter->li_pos = *pos + 1; |
|
percpu_down_write(&file_rwsem); |
|
spin_lock(&blocked_lock_lock); |
|
return seq_hlist_start_percpu(&file_lock_list.hlist, &iter->li_cpu, *pos); |
|
} |
|
|
|
static void *locks_next(struct seq_file *f, void *v, loff_t *pos) |
|
{ |
|
struct locks_iterator *iter = f->private; |
|
|
|
++iter->li_pos; |
|
return seq_hlist_next_percpu(v, &file_lock_list.hlist, &iter->li_cpu, pos); |
|
} |
|
|
|
static void locks_stop(struct seq_file *f, void *v) |
|
__releases(&blocked_lock_lock) |
|
{ |
|
spin_unlock(&blocked_lock_lock); |
|
percpu_up_write(&file_rwsem); |
|
} |
|
|
|
static const struct seq_operations locks_seq_operations = { |
|
.start = locks_start, |
|
.next = locks_next, |
|
.stop = locks_stop, |
|
.show = locks_show, |
|
}; |
|
|
|
static int __init proc_locks_init(void) |
|
{ |
|
proc_create_seq_private("locks", 0, NULL, &locks_seq_operations, |
|
sizeof(struct locks_iterator), NULL); |
|
return 0; |
|
} |
|
fs_initcall(proc_locks_init); |
|
#endif |
|
|
|
static int __init filelock_init(void) |
|
{ |
|
int i; |
|
|
|
flctx_cache = kmem_cache_create("file_lock_ctx", |
|
sizeof(struct file_lock_context), 0, SLAB_PANIC, NULL); |
|
|
|
filelock_cache = kmem_cache_create("file_lock_cache", |
|
sizeof(struct file_lock), 0, SLAB_PANIC, NULL); |
|
|
|
for_each_possible_cpu(i) { |
|
struct file_lock_list_struct *fll = per_cpu_ptr(&file_lock_list, i); |
|
|
|
spin_lock_init(&fll->lock); |
|
INIT_HLIST_HEAD(&fll->hlist); |
|
} |
|
|
|
lease_notifier_chain_init(); |
|
return 0; |
|
} |
|
core_initcall(filelock_init);
|
|
|