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1568 lines
41 KiB
1568 lines
41 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* fs/libfs.c |
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* Library for filesystems writers. |
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*/ |
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|
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#include <linux/blkdev.h> |
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#include <linux/export.h> |
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#include <linux/pagemap.h> |
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#include <linux/slab.h> |
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#include <linux/cred.h> |
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#include <linux/mount.h> |
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#include <linux/vfs.h> |
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#include <linux/quotaops.h> |
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#include <linux/mutex.h> |
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#include <linux/namei.h> |
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#include <linux/exportfs.h> |
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#include <linux/iversion.h> |
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#include <linux/writeback.h> |
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#include <linux/buffer_head.h> /* sync_mapping_buffers */ |
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#include <linux/fs_context.h> |
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#include <linux/pseudo_fs.h> |
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#include <linux/fsnotify.h> |
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#include <linux/unicode.h> |
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#include <linux/fscrypt.h> |
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|
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#include <linux/uaccess.h> |
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|
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#include "internal.h" |
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|
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int simple_getattr(struct user_namespace *mnt_userns, const struct path *path, |
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struct kstat *stat, u32 request_mask, |
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unsigned int query_flags) |
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{ |
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struct inode *inode = d_inode(path->dentry); |
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generic_fillattr(&init_user_ns, inode, stat); |
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stat->blocks = inode->i_mapping->nrpages << (PAGE_SHIFT - 9); |
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return 0; |
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} |
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EXPORT_SYMBOL(simple_getattr); |
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|
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int simple_statfs(struct dentry *dentry, struct kstatfs *buf) |
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{ |
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buf->f_type = dentry->d_sb->s_magic; |
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buf->f_bsize = PAGE_SIZE; |
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buf->f_namelen = NAME_MAX; |
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return 0; |
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} |
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EXPORT_SYMBOL(simple_statfs); |
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|
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/* |
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* Retaining negative dentries for an in-memory filesystem just wastes |
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* memory and lookup time: arrange for them to be deleted immediately. |
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*/ |
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int always_delete_dentry(const struct dentry *dentry) |
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{ |
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return 1; |
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} |
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EXPORT_SYMBOL(always_delete_dentry); |
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|
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const struct dentry_operations simple_dentry_operations = { |
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.d_delete = always_delete_dentry, |
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}; |
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EXPORT_SYMBOL(simple_dentry_operations); |
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|
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/* |
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* Lookup the data. This is trivial - if the dentry didn't already |
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* exist, we know it is negative. Set d_op to delete negative dentries. |
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*/ |
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struct dentry *simple_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) |
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{ |
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if (dentry->d_name.len > NAME_MAX) |
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return ERR_PTR(-ENAMETOOLONG); |
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if (!dentry->d_sb->s_d_op) |
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d_set_d_op(dentry, &simple_dentry_operations); |
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d_add(dentry, NULL); |
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return NULL; |
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} |
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EXPORT_SYMBOL(simple_lookup); |
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|
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int dcache_dir_open(struct inode *inode, struct file *file) |
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{ |
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file->private_data = d_alloc_cursor(file->f_path.dentry); |
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|
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return file->private_data ? 0 : -ENOMEM; |
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} |
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EXPORT_SYMBOL(dcache_dir_open); |
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|
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int dcache_dir_close(struct inode *inode, struct file *file) |
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{ |
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dput(file->private_data); |
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return 0; |
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} |
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EXPORT_SYMBOL(dcache_dir_close); |
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|
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/* parent is locked at least shared */ |
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/* |
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* Returns an element of siblings' list. |
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* We are looking for <count>th positive after <p>; if |
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* found, dentry is grabbed and returned to caller. |
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* If no such element exists, NULL is returned. |
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*/ |
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static struct dentry *scan_positives(struct dentry *cursor, |
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struct list_head *p, |
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loff_t count, |
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struct dentry *last) |
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{ |
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struct dentry *dentry = cursor->d_parent, *found = NULL; |
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|
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spin_lock(&dentry->d_lock); |
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while ((p = p->next) != &dentry->d_subdirs) { |
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struct dentry *d = list_entry(p, struct dentry, d_child); |
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// we must at least skip cursors, to avoid livelocks |
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if (d->d_flags & DCACHE_DENTRY_CURSOR) |
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continue; |
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if (simple_positive(d) && !--count) { |
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spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED); |
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if (simple_positive(d)) |
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found = dget_dlock(d); |
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spin_unlock(&d->d_lock); |
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if (likely(found)) |
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break; |
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count = 1; |
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} |
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if (need_resched()) { |
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list_move(&cursor->d_child, p); |
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p = &cursor->d_child; |
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spin_unlock(&dentry->d_lock); |
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cond_resched(); |
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spin_lock(&dentry->d_lock); |
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} |
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} |
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spin_unlock(&dentry->d_lock); |
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dput(last); |
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return found; |
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} |
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|
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loff_t dcache_dir_lseek(struct file *file, loff_t offset, int whence) |
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{ |
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struct dentry *dentry = file->f_path.dentry; |
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switch (whence) { |
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case 1: |
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offset += file->f_pos; |
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fallthrough; |
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case 0: |
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if (offset >= 0) |
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break; |
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fallthrough; |
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default: |
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return -EINVAL; |
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} |
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if (offset != file->f_pos) { |
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struct dentry *cursor = file->private_data; |
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struct dentry *to = NULL; |
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|
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inode_lock_shared(dentry->d_inode); |
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|
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if (offset > 2) |
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to = scan_positives(cursor, &dentry->d_subdirs, |
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offset - 2, NULL); |
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spin_lock(&dentry->d_lock); |
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if (to) |
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list_move(&cursor->d_child, &to->d_child); |
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else |
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list_del_init(&cursor->d_child); |
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spin_unlock(&dentry->d_lock); |
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dput(to); |
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|
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file->f_pos = offset; |
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|
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inode_unlock_shared(dentry->d_inode); |
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} |
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return offset; |
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} |
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EXPORT_SYMBOL(dcache_dir_lseek); |
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|
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/* Relationship between i_mode and the DT_xxx types */ |
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static inline unsigned char dt_type(struct inode *inode) |
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{ |
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return (inode->i_mode >> 12) & 15; |
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} |
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|
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/* |
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* Directory is locked and all positive dentries in it are safe, since |
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* for ramfs-type trees they can't go away without unlink() or rmdir(), |
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* both impossible due to the lock on directory. |
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*/ |
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|
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int dcache_readdir(struct file *file, struct dir_context *ctx) |
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{ |
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struct dentry *dentry = file->f_path.dentry; |
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struct dentry *cursor = file->private_data; |
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struct list_head *anchor = &dentry->d_subdirs; |
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struct dentry *next = NULL; |
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struct list_head *p; |
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|
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if (!dir_emit_dots(file, ctx)) |
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return 0; |
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|
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if (ctx->pos == 2) |
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p = anchor; |
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else if (!list_empty(&cursor->d_child)) |
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p = &cursor->d_child; |
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else |
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return 0; |
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|
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while ((next = scan_positives(cursor, p, 1, next)) != NULL) { |
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if (!dir_emit(ctx, next->d_name.name, next->d_name.len, |
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d_inode(next)->i_ino, dt_type(d_inode(next)))) |
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break; |
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ctx->pos++; |
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p = &next->d_child; |
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} |
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spin_lock(&dentry->d_lock); |
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if (next) |
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list_move_tail(&cursor->d_child, &next->d_child); |
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else |
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list_del_init(&cursor->d_child); |
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spin_unlock(&dentry->d_lock); |
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dput(next); |
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|
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return 0; |
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} |
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EXPORT_SYMBOL(dcache_readdir); |
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|
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ssize_t generic_read_dir(struct file *filp, char __user *buf, size_t siz, loff_t *ppos) |
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{ |
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return -EISDIR; |
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} |
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EXPORT_SYMBOL(generic_read_dir); |
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|
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const struct file_operations simple_dir_operations = { |
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.open = dcache_dir_open, |
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.release = dcache_dir_close, |
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.llseek = dcache_dir_lseek, |
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.read = generic_read_dir, |
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.iterate_shared = dcache_readdir, |
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.fsync = noop_fsync, |
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}; |
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EXPORT_SYMBOL(simple_dir_operations); |
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|
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const struct inode_operations simple_dir_inode_operations = { |
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.lookup = simple_lookup, |
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}; |
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EXPORT_SYMBOL(simple_dir_inode_operations); |
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|
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static struct dentry *find_next_child(struct dentry *parent, struct dentry *prev) |
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{ |
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struct dentry *child = NULL; |
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struct list_head *p = prev ? &prev->d_child : &parent->d_subdirs; |
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|
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spin_lock(&parent->d_lock); |
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while ((p = p->next) != &parent->d_subdirs) { |
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struct dentry *d = container_of(p, struct dentry, d_child); |
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if (simple_positive(d)) { |
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spin_lock_nested(&d->d_lock, DENTRY_D_LOCK_NESTED); |
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if (simple_positive(d)) |
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child = dget_dlock(d); |
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spin_unlock(&d->d_lock); |
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if (likely(child)) |
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break; |
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} |
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} |
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spin_unlock(&parent->d_lock); |
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dput(prev); |
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return child; |
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} |
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|
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void simple_recursive_removal(struct dentry *dentry, |
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void (*callback)(struct dentry *)) |
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{ |
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struct dentry *this = dget(dentry); |
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while (true) { |
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struct dentry *victim = NULL, *child; |
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struct inode *inode = this->d_inode; |
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|
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inode_lock(inode); |
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if (d_is_dir(this)) |
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inode->i_flags |= S_DEAD; |
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while ((child = find_next_child(this, victim)) == NULL) { |
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// kill and ascend |
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// update metadata while it's still locked |
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inode->i_ctime = current_time(inode); |
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clear_nlink(inode); |
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inode_unlock(inode); |
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victim = this; |
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this = this->d_parent; |
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inode = this->d_inode; |
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inode_lock(inode); |
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if (simple_positive(victim)) { |
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d_invalidate(victim); // avoid lost mounts |
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if (d_is_dir(victim)) |
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fsnotify_rmdir(inode, victim); |
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else |
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fsnotify_unlink(inode, victim); |
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if (callback) |
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callback(victim); |
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dput(victim); // unpin it |
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} |
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if (victim == dentry) { |
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inode->i_ctime = inode->i_mtime = |
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current_time(inode); |
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if (d_is_dir(dentry)) |
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drop_nlink(inode); |
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inode_unlock(inode); |
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dput(dentry); |
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return; |
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} |
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} |
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inode_unlock(inode); |
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this = child; |
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} |
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} |
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EXPORT_SYMBOL(simple_recursive_removal); |
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|
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static const struct super_operations simple_super_operations = { |
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.statfs = simple_statfs, |
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}; |
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|
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static int pseudo_fs_fill_super(struct super_block *s, struct fs_context *fc) |
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{ |
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struct pseudo_fs_context *ctx = fc->fs_private; |
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struct inode *root; |
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|
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s->s_maxbytes = MAX_LFS_FILESIZE; |
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s->s_blocksize = PAGE_SIZE; |
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s->s_blocksize_bits = PAGE_SHIFT; |
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s->s_magic = ctx->magic; |
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s->s_op = ctx->ops ?: &simple_super_operations; |
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s->s_xattr = ctx->xattr; |
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s->s_time_gran = 1; |
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root = new_inode(s); |
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if (!root) |
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return -ENOMEM; |
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|
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/* |
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* since this is the first inode, make it number 1. New inodes created |
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* after this must take care not to collide with it (by passing |
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* max_reserved of 1 to iunique). |
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*/ |
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root->i_ino = 1; |
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root->i_mode = S_IFDIR | S_IRUSR | S_IWUSR; |
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root->i_atime = root->i_mtime = root->i_ctime = current_time(root); |
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s->s_root = d_make_root(root); |
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if (!s->s_root) |
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return -ENOMEM; |
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s->s_d_op = ctx->dops; |
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return 0; |
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} |
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static int pseudo_fs_get_tree(struct fs_context *fc) |
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{ |
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return get_tree_nodev(fc, pseudo_fs_fill_super); |
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} |
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|
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static void pseudo_fs_free(struct fs_context *fc) |
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{ |
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kfree(fc->fs_private); |
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} |
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|
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static const struct fs_context_operations pseudo_fs_context_ops = { |
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.free = pseudo_fs_free, |
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.get_tree = pseudo_fs_get_tree, |
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}; |
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|
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/* |
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* Common helper for pseudo-filesystems (sockfs, pipefs, bdev - stuff that |
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* will never be mountable) |
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*/ |
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struct pseudo_fs_context *init_pseudo(struct fs_context *fc, |
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unsigned long magic) |
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{ |
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struct pseudo_fs_context *ctx; |
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|
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ctx = kzalloc(sizeof(struct pseudo_fs_context), GFP_KERNEL); |
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if (likely(ctx)) { |
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ctx->magic = magic; |
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fc->fs_private = ctx; |
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fc->ops = &pseudo_fs_context_ops; |
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fc->sb_flags |= SB_NOUSER; |
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fc->global = true; |
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} |
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return ctx; |
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} |
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EXPORT_SYMBOL(init_pseudo); |
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|
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int simple_open(struct inode *inode, struct file *file) |
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{ |
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if (inode->i_private) |
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file->private_data = inode->i_private; |
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return 0; |
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} |
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EXPORT_SYMBOL(simple_open); |
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|
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int simple_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) |
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{ |
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struct inode *inode = d_inode(old_dentry); |
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|
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inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode); |
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inc_nlink(inode); |
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ihold(inode); |
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dget(dentry); |
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d_instantiate(dentry, inode); |
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return 0; |
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} |
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EXPORT_SYMBOL(simple_link); |
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|
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int simple_empty(struct dentry *dentry) |
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{ |
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struct dentry *child; |
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int ret = 0; |
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|
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spin_lock(&dentry->d_lock); |
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list_for_each_entry(child, &dentry->d_subdirs, d_child) { |
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spin_lock_nested(&child->d_lock, DENTRY_D_LOCK_NESTED); |
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if (simple_positive(child)) { |
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spin_unlock(&child->d_lock); |
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goto out; |
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} |
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spin_unlock(&child->d_lock); |
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} |
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ret = 1; |
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out: |
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spin_unlock(&dentry->d_lock); |
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return ret; |
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} |
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EXPORT_SYMBOL(simple_empty); |
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|
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int simple_unlink(struct inode *dir, struct dentry *dentry) |
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{ |
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struct inode *inode = d_inode(dentry); |
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|
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inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode); |
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drop_nlink(inode); |
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dput(dentry); |
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return 0; |
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} |
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EXPORT_SYMBOL(simple_unlink); |
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|
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int simple_rmdir(struct inode *dir, struct dentry *dentry) |
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{ |
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if (!simple_empty(dentry)) |
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return -ENOTEMPTY; |
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|
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drop_nlink(d_inode(dentry)); |
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simple_unlink(dir, dentry); |
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drop_nlink(dir); |
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return 0; |
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} |
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EXPORT_SYMBOL(simple_rmdir); |
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|
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int simple_rename_exchange(struct inode *old_dir, struct dentry *old_dentry, |
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struct inode *new_dir, struct dentry *new_dentry) |
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{ |
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bool old_is_dir = d_is_dir(old_dentry); |
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bool new_is_dir = d_is_dir(new_dentry); |
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|
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if (old_dir != new_dir && old_is_dir != new_is_dir) { |
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if (old_is_dir) { |
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drop_nlink(old_dir); |
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inc_nlink(new_dir); |
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} else { |
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drop_nlink(new_dir); |
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inc_nlink(old_dir); |
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} |
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} |
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old_dir->i_ctime = old_dir->i_mtime = |
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new_dir->i_ctime = new_dir->i_mtime = |
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d_inode(old_dentry)->i_ctime = |
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d_inode(new_dentry)->i_ctime = current_time(old_dir); |
|
|
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return 0; |
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} |
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EXPORT_SYMBOL_GPL(simple_rename_exchange); |
|
|
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int simple_rename(struct user_namespace *mnt_userns, struct inode *old_dir, |
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struct dentry *old_dentry, struct inode *new_dir, |
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struct dentry *new_dentry, unsigned int flags) |
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{ |
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struct inode *inode = d_inode(old_dentry); |
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int they_are_dirs = d_is_dir(old_dentry); |
|
|
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if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE)) |
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return -EINVAL; |
|
|
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if (flags & RENAME_EXCHANGE) |
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return simple_rename_exchange(old_dir, old_dentry, new_dir, new_dentry); |
|
|
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if (!simple_empty(new_dentry)) |
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return -ENOTEMPTY; |
|
|
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if (d_really_is_positive(new_dentry)) { |
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simple_unlink(new_dir, new_dentry); |
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if (they_are_dirs) { |
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drop_nlink(d_inode(new_dentry)); |
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drop_nlink(old_dir); |
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} |
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} else if (they_are_dirs) { |
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drop_nlink(old_dir); |
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inc_nlink(new_dir); |
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} |
|
|
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old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime = |
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new_dir->i_mtime = inode->i_ctime = current_time(old_dir); |
|
|
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return 0; |
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} |
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EXPORT_SYMBOL(simple_rename); |
|
|
|
/** |
|
* simple_setattr - setattr for simple filesystem |
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* @mnt_userns: user namespace of the target mount |
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* @dentry: dentry |
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* @iattr: iattr structure |
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* |
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* Returns 0 on success, -error on failure. |
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* |
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* simple_setattr is a simple ->setattr implementation without a proper |
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* implementation of size changes. |
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* |
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* It can either be used for in-memory filesystems or special files |
|
* on simple regular filesystems. Anything that needs to change on-disk |
|
* or wire state on size changes needs its own setattr method. |
|
*/ |
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int simple_setattr(struct user_namespace *mnt_userns, struct dentry *dentry, |
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struct iattr *iattr) |
|
{ |
|
struct inode *inode = d_inode(dentry); |
|
int error; |
|
|
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error = setattr_prepare(mnt_userns, dentry, iattr); |
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if (error) |
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return error; |
|
|
|
if (iattr->ia_valid & ATTR_SIZE) |
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truncate_setsize(inode, iattr->ia_size); |
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setattr_copy(mnt_userns, inode, iattr); |
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mark_inode_dirty(inode); |
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return 0; |
|
} |
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EXPORT_SYMBOL(simple_setattr); |
|
|
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static int simple_read_folio(struct file *file, struct folio *folio) |
|
{ |
|
folio_zero_range(folio, 0, folio_size(folio)); |
|
flush_dcache_folio(folio); |
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folio_mark_uptodate(folio); |
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folio_unlock(folio); |
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return 0; |
|
} |
|
|
|
int simple_write_begin(struct file *file, struct address_space *mapping, |
|
loff_t pos, unsigned len, |
|
struct page **pagep, void **fsdata) |
|
{ |
|
struct page *page; |
|
pgoff_t index; |
|
|
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index = pos >> PAGE_SHIFT; |
|
|
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page = grab_cache_page_write_begin(mapping, index); |
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if (!page) |
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return -ENOMEM; |
|
|
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*pagep = page; |
|
|
|
if (!PageUptodate(page) && (len != PAGE_SIZE)) { |
|
unsigned from = pos & (PAGE_SIZE - 1); |
|
|
|
zero_user_segments(page, 0, from, from + len, PAGE_SIZE); |
|
} |
|
return 0; |
|
} |
|
EXPORT_SYMBOL(simple_write_begin); |
|
|
|
/** |
|
* simple_write_end - .write_end helper for non-block-device FSes |
|
* @file: See .write_end of address_space_operations |
|
* @mapping: " |
|
* @pos: " |
|
* @len: " |
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* @copied: " |
|
* @page: " |
|
* @fsdata: " |
|
* |
|
* simple_write_end does the minimum needed for updating a page after writing is |
|
* done. It has the same API signature as the .write_end of |
|
* address_space_operations vector. So it can just be set onto .write_end for |
|
* FSes that don't need any other processing. i_mutex is assumed to be held. |
|
* Block based filesystems should use generic_write_end(). |
|
* NOTE: Even though i_size might get updated by this function, mark_inode_dirty |
|
* is not called, so a filesystem that actually does store data in .write_inode |
|
* should extend on what's done here with a call to mark_inode_dirty() in the |
|
* case that i_size has changed. |
|
* |
|
* Use *ONLY* with simple_read_folio() |
|
*/ |
|
static int simple_write_end(struct file *file, struct address_space *mapping, |
|
loff_t pos, unsigned len, unsigned copied, |
|
struct page *page, void *fsdata) |
|
{ |
|
struct inode *inode = page->mapping->host; |
|
loff_t last_pos = pos + copied; |
|
|
|
/* zero the stale part of the page if we did a short copy */ |
|
if (!PageUptodate(page)) { |
|
if (copied < len) { |
|
unsigned from = pos & (PAGE_SIZE - 1); |
|
|
|
zero_user(page, from + copied, len - copied); |
|
} |
|
SetPageUptodate(page); |
|
} |
|
/* |
|
* No need to use i_size_read() here, the i_size |
|
* cannot change under us because we hold the i_mutex. |
|
*/ |
|
if (last_pos > inode->i_size) |
|
i_size_write(inode, last_pos); |
|
|
|
set_page_dirty(page); |
|
unlock_page(page); |
|
put_page(page); |
|
|
|
return copied; |
|
} |
|
|
|
/* |
|
* Provides ramfs-style behavior: data in the pagecache, but no writeback. |
|
*/ |
|
const struct address_space_operations ram_aops = { |
|
.read_folio = simple_read_folio, |
|
.write_begin = simple_write_begin, |
|
.write_end = simple_write_end, |
|
.dirty_folio = noop_dirty_folio, |
|
}; |
|
EXPORT_SYMBOL(ram_aops); |
|
|
|
/* |
|
* the inodes created here are not hashed. If you use iunique to generate |
|
* unique inode values later for this filesystem, then you must take care |
|
* to pass it an appropriate max_reserved value to avoid collisions. |
|
*/ |
|
int simple_fill_super(struct super_block *s, unsigned long magic, |
|
const struct tree_descr *files) |
|
{ |
|
struct inode *inode; |
|
struct dentry *root; |
|
struct dentry *dentry; |
|
int i; |
|
|
|
s->s_blocksize = PAGE_SIZE; |
|
s->s_blocksize_bits = PAGE_SHIFT; |
|
s->s_magic = magic; |
|
s->s_op = &simple_super_operations; |
|
s->s_time_gran = 1; |
|
|
|
inode = new_inode(s); |
|
if (!inode) |
|
return -ENOMEM; |
|
/* |
|
* because the root inode is 1, the files array must not contain an |
|
* entry at index 1 |
|
*/ |
|
inode->i_ino = 1; |
|
inode->i_mode = S_IFDIR | 0755; |
|
inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); |
|
inode->i_op = &simple_dir_inode_operations; |
|
inode->i_fop = &simple_dir_operations; |
|
set_nlink(inode, 2); |
|
root = d_make_root(inode); |
|
if (!root) |
|
return -ENOMEM; |
|
for (i = 0; !files->name || files->name[0]; i++, files++) { |
|
if (!files->name) |
|
continue; |
|
|
|
/* warn if it tries to conflict with the root inode */ |
|
if (unlikely(i == 1)) |
|
printk(KERN_WARNING "%s: %s passed in a files array" |
|
"with an index of 1!\n", __func__, |
|
s->s_type->name); |
|
|
|
dentry = d_alloc_name(root, files->name); |
|
if (!dentry) |
|
goto out; |
|
inode = new_inode(s); |
|
if (!inode) { |
|
dput(dentry); |
|
goto out; |
|
} |
|
inode->i_mode = S_IFREG | files->mode; |
|
inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); |
|
inode->i_fop = files->ops; |
|
inode->i_ino = i; |
|
d_add(dentry, inode); |
|
} |
|
s->s_root = root; |
|
return 0; |
|
out: |
|
d_genocide(root); |
|
shrink_dcache_parent(root); |
|
dput(root); |
|
return -ENOMEM; |
|
} |
|
EXPORT_SYMBOL(simple_fill_super); |
|
|
|
static DEFINE_SPINLOCK(pin_fs_lock); |
|
|
|
int simple_pin_fs(struct file_system_type *type, struct vfsmount **mount, int *count) |
|
{ |
|
struct vfsmount *mnt = NULL; |
|
spin_lock(&pin_fs_lock); |
|
if (unlikely(!*mount)) { |
|
spin_unlock(&pin_fs_lock); |
|
mnt = vfs_kern_mount(type, SB_KERNMOUNT, type->name, NULL); |
|
if (IS_ERR(mnt)) |
|
return PTR_ERR(mnt); |
|
spin_lock(&pin_fs_lock); |
|
if (!*mount) |
|
*mount = mnt; |
|
} |
|
mntget(*mount); |
|
++*count; |
|
spin_unlock(&pin_fs_lock); |
|
mntput(mnt); |
|
return 0; |
|
} |
|
EXPORT_SYMBOL(simple_pin_fs); |
|
|
|
void simple_release_fs(struct vfsmount **mount, int *count) |
|
{ |
|
struct vfsmount *mnt; |
|
spin_lock(&pin_fs_lock); |
|
mnt = *mount; |
|
if (!--*count) |
|
*mount = NULL; |
|
spin_unlock(&pin_fs_lock); |
|
mntput(mnt); |
|
} |
|
EXPORT_SYMBOL(simple_release_fs); |
|
|
|
/** |
|
* simple_read_from_buffer - copy data from the buffer to user space |
|
* @to: the user space buffer to read to |
|
* @count: the maximum number of bytes to read |
|
* @ppos: the current position in the buffer |
|
* @from: the buffer to read from |
|
* @available: the size of the buffer |
|
* |
|
* The simple_read_from_buffer() function reads up to @count bytes from the |
|
* buffer @from at offset @ppos into the user space address starting at @to. |
|
* |
|
* On success, the number of bytes read is returned and the offset @ppos is |
|
* advanced by this number, or negative value is returned on error. |
|
**/ |
|
ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos, |
|
const void *from, size_t available) |
|
{ |
|
loff_t pos = *ppos; |
|
size_t ret; |
|
|
|
if (pos < 0) |
|
return -EINVAL; |
|
if (pos >= available || !count) |
|
return 0; |
|
if (count > available - pos) |
|
count = available - pos; |
|
ret = copy_to_user(to, from + pos, count); |
|
if (ret == count) |
|
return -EFAULT; |
|
count -= ret; |
|
*ppos = pos + count; |
|
return count; |
|
} |
|
EXPORT_SYMBOL(simple_read_from_buffer); |
|
|
|
/** |
|
* simple_write_to_buffer - copy data from user space to the buffer |
|
* @to: the buffer to write to |
|
* @available: the size of the buffer |
|
* @ppos: the current position in the buffer |
|
* @from: the user space buffer to read from |
|
* @count: the maximum number of bytes to read |
|
* |
|
* The simple_write_to_buffer() function reads up to @count bytes from the user |
|
* space address starting at @from into the buffer @to at offset @ppos. |
|
* |
|
* On success, the number of bytes written is returned and the offset @ppos is |
|
* advanced by this number, or negative value is returned on error. |
|
**/ |
|
ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos, |
|
const void __user *from, size_t count) |
|
{ |
|
loff_t pos = *ppos; |
|
size_t res; |
|
|
|
if (pos < 0) |
|
return -EINVAL; |
|
if (pos >= available || !count) |
|
return 0; |
|
if (count > available - pos) |
|
count = available - pos; |
|
res = copy_from_user(to + pos, from, count); |
|
if (res == count) |
|
return -EFAULT; |
|
count -= res; |
|
*ppos = pos + count; |
|
return count; |
|
} |
|
EXPORT_SYMBOL(simple_write_to_buffer); |
|
|
|
/** |
|
* memory_read_from_buffer - copy data from the buffer |
|
* @to: the kernel space buffer to read to |
|
* @count: the maximum number of bytes to read |
|
* @ppos: the current position in the buffer |
|
* @from: the buffer to read from |
|
* @available: the size of the buffer |
|
* |
|
* The memory_read_from_buffer() function reads up to @count bytes from the |
|
* buffer @from at offset @ppos into the kernel space address starting at @to. |
|
* |
|
* On success, the number of bytes read is returned and the offset @ppos is |
|
* advanced by this number, or negative value is returned on error. |
|
**/ |
|
ssize_t memory_read_from_buffer(void *to, size_t count, loff_t *ppos, |
|
const void *from, size_t available) |
|
{ |
|
loff_t pos = *ppos; |
|
|
|
if (pos < 0) |
|
return -EINVAL; |
|
if (pos >= available) |
|
return 0; |
|
if (count > available - pos) |
|
count = available - pos; |
|
memcpy(to, from + pos, count); |
|
*ppos = pos + count; |
|
|
|
return count; |
|
} |
|
EXPORT_SYMBOL(memory_read_from_buffer); |
|
|
|
/* |
|
* Transaction based IO. |
|
* The file expects a single write which triggers the transaction, and then |
|
* possibly a read which collects the result - which is stored in a |
|
* file-local buffer. |
|
*/ |
|
|
|
void simple_transaction_set(struct file *file, size_t n) |
|
{ |
|
struct simple_transaction_argresp *ar = file->private_data; |
|
|
|
BUG_ON(n > SIMPLE_TRANSACTION_LIMIT); |
|
|
|
/* |
|
* The barrier ensures that ar->size will really remain zero until |
|
* ar->data is ready for reading. |
|
*/ |
|
smp_mb(); |
|
ar->size = n; |
|
} |
|
EXPORT_SYMBOL(simple_transaction_set); |
|
|
|
char *simple_transaction_get(struct file *file, const char __user *buf, size_t size) |
|
{ |
|
struct simple_transaction_argresp *ar; |
|
static DEFINE_SPINLOCK(simple_transaction_lock); |
|
|
|
if (size > SIMPLE_TRANSACTION_LIMIT - 1) |
|
return ERR_PTR(-EFBIG); |
|
|
|
ar = (struct simple_transaction_argresp *)get_zeroed_page(GFP_KERNEL); |
|
if (!ar) |
|
return ERR_PTR(-ENOMEM); |
|
|
|
spin_lock(&simple_transaction_lock); |
|
|
|
/* only one write allowed per open */ |
|
if (file->private_data) { |
|
spin_unlock(&simple_transaction_lock); |
|
free_page((unsigned long)ar); |
|
return ERR_PTR(-EBUSY); |
|
} |
|
|
|
file->private_data = ar; |
|
|
|
spin_unlock(&simple_transaction_lock); |
|
|
|
if (copy_from_user(ar->data, buf, size)) |
|
return ERR_PTR(-EFAULT); |
|
|
|
return ar->data; |
|
} |
|
EXPORT_SYMBOL(simple_transaction_get); |
|
|
|
ssize_t simple_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos) |
|
{ |
|
struct simple_transaction_argresp *ar = file->private_data; |
|
|
|
if (!ar) |
|
return 0; |
|
return simple_read_from_buffer(buf, size, pos, ar->data, ar->size); |
|
} |
|
EXPORT_SYMBOL(simple_transaction_read); |
|
|
|
int simple_transaction_release(struct inode *inode, struct file *file) |
|
{ |
|
free_page((unsigned long)file->private_data); |
|
return 0; |
|
} |
|
EXPORT_SYMBOL(simple_transaction_release); |
|
|
|
/* Simple attribute files */ |
|
|
|
struct simple_attr { |
|
int (*get)(void *, u64 *); |
|
int (*set)(void *, u64); |
|
char get_buf[24]; /* enough to store a u64 and "\n\0" */ |
|
char set_buf[24]; |
|
void *data; |
|
const char *fmt; /* format for read operation */ |
|
struct mutex mutex; /* protects access to these buffers */ |
|
}; |
|
|
|
/* simple_attr_open is called by an actual attribute open file operation |
|
* to set the attribute specific access operations. */ |
|
int simple_attr_open(struct inode *inode, struct file *file, |
|
int (*get)(void *, u64 *), int (*set)(void *, u64), |
|
const char *fmt) |
|
{ |
|
struct simple_attr *attr; |
|
|
|
attr = kzalloc(sizeof(*attr), GFP_KERNEL); |
|
if (!attr) |
|
return -ENOMEM; |
|
|
|
attr->get = get; |
|
attr->set = set; |
|
attr->data = inode->i_private; |
|
attr->fmt = fmt; |
|
mutex_init(&attr->mutex); |
|
|
|
file->private_data = attr; |
|
|
|
return nonseekable_open(inode, file); |
|
} |
|
EXPORT_SYMBOL_GPL(simple_attr_open); |
|
|
|
int simple_attr_release(struct inode *inode, struct file *file) |
|
{ |
|
kfree(file->private_data); |
|
return 0; |
|
} |
|
EXPORT_SYMBOL_GPL(simple_attr_release); /* GPL-only? This? Really? */ |
|
|
|
/* read from the buffer that is filled with the get function */ |
|
ssize_t simple_attr_read(struct file *file, char __user *buf, |
|
size_t len, loff_t *ppos) |
|
{ |
|
struct simple_attr *attr; |
|
size_t size; |
|
ssize_t ret; |
|
|
|
attr = file->private_data; |
|
|
|
if (!attr->get) |
|
return -EACCES; |
|
|
|
ret = mutex_lock_interruptible(&attr->mutex); |
|
if (ret) |
|
return ret; |
|
|
|
if (*ppos && attr->get_buf[0]) { |
|
/* continued read */ |
|
size = strlen(attr->get_buf); |
|
} else { |
|
/* first read */ |
|
u64 val; |
|
ret = attr->get(attr->data, &val); |
|
if (ret) |
|
goto out; |
|
|
|
size = scnprintf(attr->get_buf, sizeof(attr->get_buf), |
|
attr->fmt, (unsigned long long)val); |
|
} |
|
|
|
ret = simple_read_from_buffer(buf, len, ppos, attr->get_buf, size); |
|
out: |
|
mutex_unlock(&attr->mutex); |
|
return ret; |
|
} |
|
EXPORT_SYMBOL_GPL(simple_attr_read); |
|
|
|
/* interpret the buffer as a number to call the set function with */ |
|
ssize_t simple_attr_write(struct file *file, const char __user *buf, |
|
size_t len, loff_t *ppos) |
|
{ |
|
struct simple_attr *attr; |
|
unsigned long long val; |
|
size_t size; |
|
ssize_t ret; |
|
|
|
attr = file->private_data; |
|
if (!attr->set) |
|
return -EACCES; |
|
|
|
ret = mutex_lock_interruptible(&attr->mutex); |
|
if (ret) |
|
return ret; |
|
|
|
ret = -EFAULT; |
|
size = min(sizeof(attr->set_buf) - 1, len); |
|
if (copy_from_user(attr->set_buf, buf, size)) |
|
goto out; |
|
|
|
attr->set_buf[size] = '\0'; |
|
ret = kstrtoull(attr->set_buf, 0, &val); |
|
if (ret) |
|
goto out; |
|
ret = attr->set(attr->data, val); |
|
if (ret == 0) |
|
ret = len; /* on success, claim we got the whole input */ |
|
out: |
|
mutex_unlock(&attr->mutex); |
|
return ret; |
|
} |
|
EXPORT_SYMBOL_GPL(simple_attr_write); |
|
|
|
/** |
|
* generic_fh_to_dentry - generic helper for the fh_to_dentry export operation |
|
* @sb: filesystem to do the file handle conversion on |
|
* @fid: file handle to convert |
|
* @fh_len: length of the file handle in bytes |
|
* @fh_type: type of file handle |
|
* @get_inode: filesystem callback to retrieve inode |
|
* |
|
* This function decodes @fid as long as it has one of the well-known |
|
* Linux filehandle types and calls @get_inode on it to retrieve the |
|
* inode for the object specified in the file handle. |
|
*/ |
|
struct dentry *generic_fh_to_dentry(struct super_block *sb, struct fid *fid, |
|
int fh_len, int fh_type, struct inode *(*get_inode) |
|
(struct super_block *sb, u64 ino, u32 gen)) |
|
{ |
|
struct inode *inode = NULL; |
|
|
|
if (fh_len < 2) |
|
return NULL; |
|
|
|
switch (fh_type) { |
|
case FILEID_INO32_GEN: |
|
case FILEID_INO32_GEN_PARENT: |
|
inode = get_inode(sb, fid->i32.ino, fid->i32.gen); |
|
break; |
|
} |
|
|
|
return d_obtain_alias(inode); |
|
} |
|
EXPORT_SYMBOL_GPL(generic_fh_to_dentry); |
|
|
|
/** |
|
* generic_fh_to_parent - generic helper for the fh_to_parent export operation |
|
* @sb: filesystem to do the file handle conversion on |
|
* @fid: file handle to convert |
|
* @fh_len: length of the file handle in bytes |
|
* @fh_type: type of file handle |
|
* @get_inode: filesystem callback to retrieve inode |
|
* |
|
* This function decodes @fid as long as it has one of the well-known |
|
* Linux filehandle types and calls @get_inode on it to retrieve the |
|
* inode for the _parent_ object specified in the file handle if it |
|
* is specified in the file handle, or NULL otherwise. |
|
*/ |
|
struct dentry *generic_fh_to_parent(struct super_block *sb, struct fid *fid, |
|
int fh_len, int fh_type, struct inode *(*get_inode) |
|
(struct super_block *sb, u64 ino, u32 gen)) |
|
{ |
|
struct inode *inode = NULL; |
|
|
|
if (fh_len <= 2) |
|
return NULL; |
|
|
|
switch (fh_type) { |
|
case FILEID_INO32_GEN_PARENT: |
|
inode = get_inode(sb, fid->i32.parent_ino, |
|
(fh_len > 3 ? fid->i32.parent_gen : 0)); |
|
break; |
|
} |
|
|
|
return d_obtain_alias(inode); |
|
} |
|
EXPORT_SYMBOL_GPL(generic_fh_to_parent); |
|
|
|
/** |
|
* __generic_file_fsync - generic fsync implementation for simple filesystems |
|
* |
|
* @file: file to synchronize |
|
* @start: start offset in bytes |
|
* @end: end offset in bytes (inclusive) |
|
* @datasync: only synchronize essential metadata if true |
|
* |
|
* This is a generic implementation of the fsync method for simple |
|
* filesystems which track all non-inode metadata in the buffers list |
|
* hanging off the address_space structure. |
|
*/ |
|
int __generic_file_fsync(struct file *file, loff_t start, loff_t end, |
|
int datasync) |
|
{ |
|
struct inode *inode = file->f_mapping->host; |
|
int err; |
|
int ret; |
|
|
|
err = file_write_and_wait_range(file, start, end); |
|
if (err) |
|
return err; |
|
|
|
inode_lock(inode); |
|
ret = sync_mapping_buffers(inode->i_mapping); |
|
if (!(inode->i_state & I_DIRTY_ALL)) |
|
goto out; |
|
if (datasync && !(inode->i_state & I_DIRTY_DATASYNC)) |
|
goto out; |
|
|
|
err = sync_inode_metadata(inode, 1); |
|
if (ret == 0) |
|
ret = err; |
|
|
|
out: |
|
inode_unlock(inode); |
|
/* check and advance again to catch errors after syncing out buffers */ |
|
err = file_check_and_advance_wb_err(file); |
|
if (ret == 0) |
|
ret = err; |
|
return ret; |
|
} |
|
EXPORT_SYMBOL(__generic_file_fsync); |
|
|
|
/** |
|
* generic_file_fsync - generic fsync implementation for simple filesystems |
|
* with flush |
|
* @file: file to synchronize |
|
* @start: start offset in bytes |
|
* @end: end offset in bytes (inclusive) |
|
* @datasync: only synchronize essential metadata if true |
|
* |
|
*/ |
|
|
|
int generic_file_fsync(struct file *file, loff_t start, loff_t end, |
|
int datasync) |
|
{ |
|
struct inode *inode = file->f_mapping->host; |
|
int err; |
|
|
|
err = __generic_file_fsync(file, start, end, datasync); |
|
if (err) |
|
return err; |
|
return blkdev_issue_flush(inode->i_sb->s_bdev); |
|
} |
|
EXPORT_SYMBOL(generic_file_fsync); |
|
|
|
/** |
|
* generic_check_addressable - Check addressability of file system |
|
* @blocksize_bits: log of file system block size |
|
* @num_blocks: number of blocks in file system |
|
* |
|
* Determine whether a file system with @num_blocks blocks (and a |
|
* block size of 2**@blocksize_bits) is addressable by the sector_t |
|
* and page cache of the system. Return 0 if so and -EFBIG otherwise. |
|
*/ |
|
int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks) |
|
{ |
|
u64 last_fs_block = num_blocks - 1; |
|
u64 last_fs_page = |
|
last_fs_block >> (PAGE_SHIFT - blocksize_bits); |
|
|
|
if (unlikely(num_blocks == 0)) |
|
return 0; |
|
|
|
if ((blocksize_bits < 9) || (blocksize_bits > PAGE_SHIFT)) |
|
return -EINVAL; |
|
|
|
if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) || |
|
(last_fs_page > (pgoff_t)(~0ULL))) { |
|
return -EFBIG; |
|
} |
|
return 0; |
|
} |
|
EXPORT_SYMBOL(generic_check_addressable); |
|
|
|
/* |
|
* No-op implementation of ->fsync for in-memory filesystems. |
|
*/ |
|
int noop_fsync(struct file *file, loff_t start, loff_t end, int datasync) |
|
{ |
|
return 0; |
|
} |
|
EXPORT_SYMBOL(noop_fsync); |
|
|
|
ssize_t noop_direct_IO(struct kiocb *iocb, struct iov_iter *iter) |
|
{ |
|
/* |
|
* iomap based filesystems support direct I/O without need for |
|
* this callback. However, it still needs to be set in |
|
* inode->a_ops so that open/fcntl know that direct I/O is |
|
* generally supported. |
|
*/ |
|
return -EINVAL; |
|
} |
|
EXPORT_SYMBOL_GPL(noop_direct_IO); |
|
|
|
/* Because kfree isn't assignment-compatible with void(void*) ;-/ */ |
|
void kfree_link(void *p) |
|
{ |
|
kfree(p); |
|
} |
|
EXPORT_SYMBOL(kfree_link); |
|
|
|
struct inode *alloc_anon_inode(struct super_block *s) |
|
{ |
|
static const struct address_space_operations anon_aops = { |
|
.dirty_folio = noop_dirty_folio, |
|
}; |
|
struct inode *inode = new_inode_pseudo(s); |
|
|
|
if (!inode) |
|
return ERR_PTR(-ENOMEM); |
|
|
|
inode->i_ino = get_next_ino(); |
|
inode->i_mapping->a_ops = &anon_aops; |
|
|
|
/* |
|
* Mark the inode dirty from the very beginning, |
|
* that way it will never be moved to the dirty |
|
* list because mark_inode_dirty() will think |
|
* that it already _is_ on the dirty list. |
|
*/ |
|
inode->i_state = I_DIRTY; |
|
inode->i_mode = S_IRUSR | S_IWUSR; |
|
inode->i_uid = current_fsuid(); |
|
inode->i_gid = current_fsgid(); |
|
inode->i_flags |= S_PRIVATE; |
|
inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); |
|
return inode; |
|
} |
|
EXPORT_SYMBOL(alloc_anon_inode); |
|
|
|
/** |
|
* simple_nosetlease - generic helper for prohibiting leases |
|
* @filp: file pointer |
|
* @arg: type of lease to obtain |
|
* @flp: new lease supplied for insertion |
|
* @priv: private data for lm_setup operation |
|
* |
|
* Generic helper for filesystems that do not wish to allow leases to be set. |
|
* All arguments are ignored and it just returns -EINVAL. |
|
*/ |
|
int |
|
simple_nosetlease(struct file *filp, long arg, struct file_lock **flp, |
|
void **priv) |
|
{ |
|
return -EINVAL; |
|
} |
|
EXPORT_SYMBOL(simple_nosetlease); |
|
|
|
/** |
|
* simple_get_link - generic helper to get the target of "fast" symlinks |
|
* @dentry: not used here |
|
* @inode: the symlink inode |
|
* @done: not used here |
|
* |
|
* Generic helper for filesystems to use for symlink inodes where a pointer to |
|
* the symlink target is stored in ->i_link. NOTE: this isn't normally called, |
|
* since as an optimization the path lookup code uses any non-NULL ->i_link |
|
* directly, without calling ->get_link(). But ->get_link() still must be set, |
|
* to mark the inode_operations as being for a symlink. |
|
* |
|
* Return: the symlink target |
|
*/ |
|
const char *simple_get_link(struct dentry *dentry, struct inode *inode, |
|
struct delayed_call *done) |
|
{ |
|
return inode->i_link; |
|
} |
|
EXPORT_SYMBOL(simple_get_link); |
|
|
|
const struct inode_operations simple_symlink_inode_operations = { |
|
.get_link = simple_get_link, |
|
}; |
|
EXPORT_SYMBOL(simple_symlink_inode_operations); |
|
|
|
/* |
|
* Operations for a permanently empty directory. |
|
*/ |
|
static struct dentry *empty_dir_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) |
|
{ |
|
return ERR_PTR(-ENOENT); |
|
} |
|
|
|
static int empty_dir_getattr(struct user_namespace *mnt_userns, |
|
const struct path *path, struct kstat *stat, |
|
u32 request_mask, unsigned int query_flags) |
|
{ |
|
struct inode *inode = d_inode(path->dentry); |
|
generic_fillattr(&init_user_ns, inode, stat); |
|
return 0; |
|
} |
|
|
|
static int empty_dir_setattr(struct user_namespace *mnt_userns, |
|
struct dentry *dentry, struct iattr *attr) |
|
{ |
|
return -EPERM; |
|
} |
|
|
|
static ssize_t empty_dir_listxattr(struct dentry *dentry, char *list, size_t size) |
|
{ |
|
return -EOPNOTSUPP; |
|
} |
|
|
|
static const struct inode_operations empty_dir_inode_operations = { |
|
.lookup = empty_dir_lookup, |
|
.permission = generic_permission, |
|
.setattr = empty_dir_setattr, |
|
.getattr = empty_dir_getattr, |
|
.listxattr = empty_dir_listxattr, |
|
}; |
|
|
|
static loff_t empty_dir_llseek(struct file *file, loff_t offset, int whence) |
|
{ |
|
/* An empty directory has two entries . and .. at offsets 0 and 1 */ |
|
return generic_file_llseek_size(file, offset, whence, 2, 2); |
|
} |
|
|
|
static int empty_dir_readdir(struct file *file, struct dir_context *ctx) |
|
{ |
|
dir_emit_dots(file, ctx); |
|
return 0; |
|
} |
|
|
|
static const struct file_operations empty_dir_operations = { |
|
.llseek = empty_dir_llseek, |
|
.read = generic_read_dir, |
|
.iterate_shared = empty_dir_readdir, |
|
.fsync = noop_fsync, |
|
}; |
|
|
|
|
|
void make_empty_dir_inode(struct inode *inode) |
|
{ |
|
set_nlink(inode, 2); |
|
inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO; |
|
inode->i_uid = GLOBAL_ROOT_UID; |
|
inode->i_gid = GLOBAL_ROOT_GID; |
|
inode->i_rdev = 0; |
|
inode->i_size = 0; |
|
inode->i_blkbits = PAGE_SHIFT; |
|
inode->i_blocks = 0; |
|
|
|
inode->i_op = &empty_dir_inode_operations; |
|
inode->i_opflags &= ~IOP_XATTR; |
|
inode->i_fop = &empty_dir_operations; |
|
} |
|
|
|
bool is_empty_dir_inode(struct inode *inode) |
|
{ |
|
return (inode->i_fop == &empty_dir_operations) && |
|
(inode->i_op == &empty_dir_inode_operations); |
|
} |
|
|
|
#if IS_ENABLED(CONFIG_UNICODE) |
|
/* |
|
* Determine if the name of a dentry should be casefolded. |
|
* |
|
* Return: if names will need casefolding |
|
*/ |
|
static bool needs_casefold(const struct inode *dir) |
|
{ |
|
return IS_CASEFOLDED(dir) && dir->i_sb->s_encoding; |
|
} |
|
|
|
/** |
|
* generic_ci_d_compare - generic d_compare implementation for casefolding filesystems |
|
* @dentry: dentry whose name we are checking against |
|
* @len: len of name of dentry |
|
* @str: str pointer to name of dentry |
|
* @name: Name to compare against |
|
* |
|
* Return: 0 if names match, 1 if mismatch, or -ERRNO |
|
*/ |
|
static int generic_ci_d_compare(const struct dentry *dentry, unsigned int len, |
|
const char *str, const struct qstr *name) |
|
{ |
|
const struct dentry *parent = READ_ONCE(dentry->d_parent); |
|
const struct inode *dir = READ_ONCE(parent->d_inode); |
|
const struct super_block *sb = dentry->d_sb; |
|
const struct unicode_map *um = sb->s_encoding; |
|
struct qstr qstr = QSTR_INIT(str, len); |
|
char strbuf[DNAME_INLINE_LEN]; |
|
int ret; |
|
|
|
if (!dir || !needs_casefold(dir)) |
|
goto fallback; |
|
/* |
|
* If the dentry name is stored in-line, then it may be concurrently |
|
* modified by a rename. If this happens, the VFS will eventually retry |
|
* the lookup, so it doesn't matter what ->d_compare() returns. |
|
* However, it's unsafe to call utf8_strncasecmp() with an unstable |
|
* string. Therefore, we have to copy the name into a temporary buffer. |
|
*/ |
|
if (len <= DNAME_INLINE_LEN - 1) { |
|
memcpy(strbuf, str, len); |
|
strbuf[len] = 0; |
|
qstr.name = strbuf; |
|
/* prevent compiler from optimizing out the temporary buffer */ |
|
barrier(); |
|
} |
|
ret = utf8_strncasecmp(um, name, &qstr); |
|
if (ret >= 0) |
|
return ret; |
|
|
|
if (sb_has_strict_encoding(sb)) |
|
return -EINVAL; |
|
fallback: |
|
if (len != name->len) |
|
return 1; |
|
return !!memcmp(str, name->name, len); |
|
} |
|
|
|
/** |
|
* generic_ci_d_hash - generic d_hash implementation for casefolding filesystems |
|
* @dentry: dentry of the parent directory |
|
* @str: qstr of name whose hash we should fill in |
|
* |
|
* Return: 0 if hash was successful or unchanged, and -EINVAL on error |
|
*/ |
|
static int generic_ci_d_hash(const struct dentry *dentry, struct qstr *str) |
|
{ |
|
const struct inode *dir = READ_ONCE(dentry->d_inode); |
|
struct super_block *sb = dentry->d_sb; |
|
const struct unicode_map *um = sb->s_encoding; |
|
int ret = 0; |
|
|
|
if (!dir || !needs_casefold(dir)) |
|
return 0; |
|
|
|
ret = utf8_casefold_hash(um, dentry, str); |
|
if (ret < 0 && sb_has_strict_encoding(sb)) |
|
return -EINVAL; |
|
return 0; |
|
} |
|
|
|
static const struct dentry_operations generic_ci_dentry_ops = { |
|
.d_hash = generic_ci_d_hash, |
|
.d_compare = generic_ci_d_compare, |
|
}; |
|
#endif |
|
|
|
#ifdef CONFIG_FS_ENCRYPTION |
|
static const struct dentry_operations generic_encrypted_dentry_ops = { |
|
.d_revalidate = fscrypt_d_revalidate, |
|
}; |
|
#endif |
|
|
|
#if defined(CONFIG_FS_ENCRYPTION) && IS_ENABLED(CONFIG_UNICODE) |
|
static const struct dentry_operations generic_encrypted_ci_dentry_ops = { |
|
.d_hash = generic_ci_d_hash, |
|
.d_compare = generic_ci_d_compare, |
|
.d_revalidate = fscrypt_d_revalidate, |
|
}; |
|
#endif |
|
|
|
/** |
|
* generic_set_encrypted_ci_d_ops - helper for setting d_ops for given dentry |
|
* @dentry: dentry to set ops on |
|
* |
|
* Casefolded directories need d_hash and d_compare set, so that the dentries |
|
* contained in them are handled case-insensitively. Note that these operations |
|
* are needed on the parent directory rather than on the dentries in it, and |
|
* while the casefolding flag can be toggled on and off on an empty directory, |
|
* dentry_operations can't be changed later. As a result, if the filesystem has |
|
* casefolding support enabled at all, we have to give all dentries the |
|
* casefolding operations even if their inode doesn't have the casefolding flag |
|
* currently (and thus the casefolding ops would be no-ops for now). |
|
* |
|
* Encryption works differently in that the only dentry operation it needs is |
|
* d_revalidate, which it only needs on dentries that have the no-key name flag. |
|
* The no-key flag can't be set "later", so we don't have to worry about that. |
|
* |
|
* Finally, to maximize compatibility with overlayfs (which isn't compatible |
|
* with certain dentry operations) and to avoid taking an unnecessary |
|
* performance hit, we use custom dentry_operations for each possible |
|
* combination rather than always installing all operations. |
|
*/ |
|
void generic_set_encrypted_ci_d_ops(struct dentry *dentry) |
|
{ |
|
#ifdef CONFIG_FS_ENCRYPTION |
|
bool needs_encrypt_ops = dentry->d_flags & DCACHE_NOKEY_NAME; |
|
#endif |
|
#if IS_ENABLED(CONFIG_UNICODE) |
|
bool needs_ci_ops = dentry->d_sb->s_encoding; |
|
#endif |
|
#if defined(CONFIG_FS_ENCRYPTION) && IS_ENABLED(CONFIG_UNICODE) |
|
if (needs_encrypt_ops && needs_ci_ops) { |
|
d_set_d_op(dentry, &generic_encrypted_ci_dentry_ops); |
|
return; |
|
} |
|
#endif |
|
#ifdef CONFIG_FS_ENCRYPTION |
|
if (needs_encrypt_ops) { |
|
d_set_d_op(dentry, &generic_encrypted_dentry_ops); |
|
return; |
|
} |
|
#endif |
|
#if IS_ENABLED(CONFIG_UNICODE) |
|
if (needs_ci_ops) { |
|
d_set_d_op(dentry, &generic_ci_dentry_ops); |
|
return; |
|
} |
|
#endif |
|
} |
|
EXPORT_SYMBOL(generic_set_encrypted_ci_d_ops); |
|
|
|
/** |
|
* inode_maybe_inc_iversion - increments i_version |
|
* @inode: inode with the i_version that should be updated |
|
* @force: increment the counter even if it's not necessary? |
|
* |
|
* Every time the inode is modified, the i_version field must be seen to have |
|
* changed by any observer. |
|
* |
|
* If "force" is set or the QUERIED flag is set, then ensure that we increment |
|
* the value, and clear the queried flag. |
|
* |
|
* In the common case where neither is set, then we can return "false" without |
|
* updating i_version. |
|
* |
|
* If this function returns false, and no other metadata has changed, then we |
|
* can avoid logging the metadata. |
|
*/ |
|
bool inode_maybe_inc_iversion(struct inode *inode, bool force) |
|
{ |
|
u64 cur, new; |
|
|
|
/* |
|
* The i_version field is not strictly ordered with any other inode |
|
* information, but the legacy inode_inc_iversion code used a spinlock |
|
* to serialize increments. |
|
* |
|
* Here, we add full memory barriers to ensure that any de-facto |
|
* ordering with other info is preserved. |
|
* |
|
* This barrier pairs with the barrier in inode_query_iversion() |
|
*/ |
|
smp_mb(); |
|
cur = inode_peek_iversion_raw(inode); |
|
do { |
|
/* If flag is clear then we needn't do anything */ |
|
if (!force && !(cur & I_VERSION_QUERIED)) |
|
return false; |
|
|
|
/* Since lowest bit is flag, add 2 to avoid it */ |
|
new = (cur & ~I_VERSION_QUERIED) + I_VERSION_INCREMENT; |
|
} while (!atomic64_try_cmpxchg(&inode->i_version, &cur, new)); |
|
return true; |
|
} |
|
EXPORT_SYMBOL(inode_maybe_inc_iversion);
|
|
|