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322 lines
7.4 KiB
322 lines
7.4 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* V9FS FID Management |
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* |
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* Copyright (C) 2007 by Latchesar Ionkov <[email protected]> |
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* Copyright (C) 2005, 2006 by Eric Van Hensbergen <[email protected]> |
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*/ |
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#include <linux/module.h> |
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#include <linux/errno.h> |
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#include <linux/fs.h> |
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#include <linux/slab.h> |
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#include <linux/sched.h> |
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#include <linux/idr.h> |
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#include <net/9p/9p.h> |
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#include <net/9p/client.h> |
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#include "v9fs.h" |
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#include "v9fs_vfs.h" |
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#include "fid.h" |
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static inline void __add_fid(struct dentry *dentry, struct p9_fid *fid) |
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{ |
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hlist_add_head(&fid->dlist, (struct hlist_head *)&dentry->d_fsdata); |
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} |
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/** |
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* v9fs_fid_add - add a fid to a dentry |
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* @dentry: dentry that the fid is being added to |
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* @fid: fid to add |
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* |
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*/ |
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void v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid) |
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{ |
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spin_lock(&dentry->d_lock); |
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__add_fid(dentry, fid); |
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spin_unlock(&dentry->d_lock); |
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} |
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/** |
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* v9fs_fid_find_inode - search for an open fid off of the inode list |
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* @inode: return a fid pointing to a specific inode |
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* @uid: return a fid belonging to the specified user |
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* |
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*/ |
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static struct p9_fid *v9fs_fid_find_inode(struct inode *inode, kuid_t uid) |
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{ |
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struct hlist_head *h; |
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struct p9_fid *fid, *ret = NULL; |
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p9_debug(P9_DEBUG_VFS, " inode: %p\n", inode); |
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spin_lock(&inode->i_lock); |
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h = (struct hlist_head *)&inode->i_private; |
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hlist_for_each_entry(fid, h, ilist) { |
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if (uid_eq(fid->uid, uid)) { |
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refcount_inc(&fid->count); |
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ret = fid; |
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break; |
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} |
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} |
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spin_unlock(&inode->i_lock); |
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return ret; |
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} |
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/** |
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* v9fs_open_fid_add - add an open fid to an inode |
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* @inode: inode that the fid is being added to |
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* @fid: fid to add |
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* |
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*/ |
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void v9fs_open_fid_add(struct inode *inode, struct p9_fid *fid) |
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{ |
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spin_lock(&inode->i_lock); |
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hlist_add_head(&fid->ilist, (struct hlist_head *)&inode->i_private); |
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spin_unlock(&inode->i_lock); |
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} |
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/** |
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* v9fs_fid_find - retrieve a fid that belongs to the specified uid |
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* @dentry: dentry to look for fid in |
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* @uid: return fid that belongs to the specified user |
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* @any: if non-zero, return any fid associated with the dentry |
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* |
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*/ |
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static struct p9_fid *v9fs_fid_find(struct dentry *dentry, kuid_t uid, int any) |
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{ |
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struct p9_fid *fid, *ret; |
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p9_debug(P9_DEBUG_VFS, " dentry: %pd (%p) uid %d any %d\n", |
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dentry, dentry, from_kuid(&init_user_ns, uid), |
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any); |
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ret = NULL; |
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/* we'll recheck under lock if there's anything to look in */ |
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if (dentry->d_fsdata) { |
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struct hlist_head *h = (struct hlist_head *)&dentry->d_fsdata; |
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spin_lock(&dentry->d_lock); |
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hlist_for_each_entry(fid, h, dlist) { |
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if (any || uid_eq(fid->uid, uid)) { |
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ret = fid; |
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refcount_inc(&ret->count); |
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break; |
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} |
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} |
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spin_unlock(&dentry->d_lock); |
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} else { |
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if (dentry->d_inode) |
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ret = v9fs_fid_find_inode(dentry->d_inode, uid); |
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} |
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return ret; |
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} |
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/* |
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* We need to hold v9ses->rename_sem as long as we hold references |
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* to returned path array. Array element contain pointers to |
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* dentry names. |
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*/ |
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static int build_path_from_dentry(struct v9fs_session_info *v9ses, |
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struct dentry *dentry, const unsigned char ***names) |
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{ |
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int n = 0, i; |
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const unsigned char **wnames; |
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struct dentry *ds; |
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for (ds = dentry; !IS_ROOT(ds); ds = ds->d_parent) |
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n++; |
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wnames = kmalloc_array(n, sizeof(char *), GFP_KERNEL); |
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if (!wnames) |
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goto err_out; |
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for (ds = dentry, i = (n-1); i >= 0; i--, ds = ds->d_parent) |
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wnames[i] = ds->d_name.name; |
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*names = wnames; |
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return n; |
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err_out: |
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return -ENOMEM; |
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} |
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static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry, |
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kuid_t uid, int any) |
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{ |
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struct dentry *ds; |
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const unsigned char **wnames, *uname; |
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int i, n, l, clone, access; |
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struct v9fs_session_info *v9ses; |
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struct p9_fid *fid, *old_fid = NULL; |
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v9ses = v9fs_dentry2v9ses(dentry); |
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access = v9ses->flags & V9FS_ACCESS_MASK; |
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fid = v9fs_fid_find(dentry, uid, any); |
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if (fid) |
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return fid; |
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/* |
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* we don't have a matching fid. To do a TWALK we need |
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* parent fid. We need to prevent rename when we want to |
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* look at the parent. |
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*/ |
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down_read(&v9ses->rename_sem); |
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ds = dentry->d_parent; |
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fid = v9fs_fid_find(ds, uid, any); |
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if (fid) { |
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/* Found the parent fid do a lookup with that */ |
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struct p9_fid *ofid = fid; |
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fid = p9_client_walk(ofid, 1, &dentry->d_name.name, 1); |
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p9_client_clunk(ofid); |
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goto fid_out; |
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} |
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up_read(&v9ses->rename_sem); |
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/* start from the root and try to do a lookup */ |
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fid = v9fs_fid_find(dentry->d_sb->s_root, uid, any); |
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if (!fid) { |
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/* the user is not attached to the fs yet */ |
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if (access == V9FS_ACCESS_SINGLE) |
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return ERR_PTR(-EPERM); |
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if (v9fs_proto_dotu(v9ses) || v9fs_proto_dotl(v9ses)) |
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uname = NULL; |
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else |
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uname = v9ses->uname; |
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fid = p9_client_attach(v9ses->clnt, NULL, uname, uid, |
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v9ses->aname); |
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if (IS_ERR(fid)) |
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return fid; |
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v9fs_fid_add(dentry->d_sb->s_root, fid); |
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} |
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/* If we are root ourself just return that */ |
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if (dentry->d_sb->s_root == dentry) { |
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refcount_inc(&fid->count); |
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return fid; |
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} |
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/* |
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* Do a multipath walk with attached root. |
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* When walking parent we need to make sure we |
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* don't have a parallel rename happening |
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*/ |
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down_read(&v9ses->rename_sem); |
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n = build_path_from_dentry(v9ses, dentry, &wnames); |
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if (n < 0) { |
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fid = ERR_PTR(n); |
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goto err_out; |
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} |
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clone = 1; |
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i = 0; |
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while (i < n) { |
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l = min(n - i, P9_MAXWELEM); |
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/* |
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* We need to hold rename lock when doing a multipath |
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* walk to ensure none of the patch component change |
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*/ |
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fid = p9_client_walk(fid, l, &wnames[i], clone); |
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if (IS_ERR(fid)) { |
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if (old_fid) { |
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/* |
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* If we fail, clunk fid which are mapping |
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* to path component and not the last component |
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* of the path. |
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*/ |
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p9_client_clunk(old_fid); |
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} |
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kfree(wnames); |
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goto err_out; |
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} |
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old_fid = fid; |
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i += l; |
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clone = 0; |
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} |
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kfree(wnames); |
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fid_out: |
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if (!IS_ERR(fid)) { |
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spin_lock(&dentry->d_lock); |
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if (d_unhashed(dentry)) { |
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spin_unlock(&dentry->d_lock); |
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p9_client_clunk(fid); |
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fid = ERR_PTR(-ENOENT); |
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} else { |
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__add_fid(dentry, fid); |
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refcount_inc(&fid->count); |
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spin_unlock(&dentry->d_lock); |
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} |
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} |
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err_out: |
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up_read(&v9ses->rename_sem); |
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return fid; |
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} |
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/** |
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* v9fs_fid_lookup - lookup for a fid, try to walk if not found |
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* @dentry: dentry to look for fid in |
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* |
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* Look for a fid in the specified dentry for the current user. |
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* If no fid is found, try to create one walking from a fid from the parent |
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* dentry (if it has one), or the root dentry. If the user haven't accessed |
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* the fs yet, attach now and walk from the root. |
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*/ |
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struct p9_fid *v9fs_fid_lookup(struct dentry *dentry) |
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{ |
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kuid_t uid; |
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int any, access; |
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struct v9fs_session_info *v9ses; |
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v9ses = v9fs_dentry2v9ses(dentry); |
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access = v9ses->flags & V9FS_ACCESS_MASK; |
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switch (access) { |
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case V9FS_ACCESS_SINGLE: |
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case V9FS_ACCESS_USER: |
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case V9FS_ACCESS_CLIENT: |
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uid = current_fsuid(); |
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any = 0; |
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break; |
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case V9FS_ACCESS_ANY: |
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uid = v9ses->uid; |
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any = 1; |
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break; |
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default: |
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uid = INVALID_UID; |
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any = 0; |
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break; |
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} |
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return v9fs_fid_lookup_with_uid(dentry, uid, any); |
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} |
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struct p9_fid *v9fs_writeback_fid(struct dentry *dentry) |
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{ |
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int err; |
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struct p9_fid *fid, *ofid; |
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ofid = v9fs_fid_lookup_with_uid(dentry, GLOBAL_ROOT_UID, 0); |
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fid = clone_fid(ofid); |
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if (IS_ERR(fid)) |
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goto error_out; |
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p9_client_clunk(ofid); |
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/* |
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* writeback fid will only be used to write back the |
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* dirty pages. We always request for the open fid in read-write |
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* mode so that a partial page write which result in page |
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* read can work. |
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*/ |
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err = p9_client_open(fid, O_RDWR); |
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if (err < 0) { |
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p9_client_clunk(fid); |
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fid = ERR_PTR(err); |
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goto error_out; |
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} |
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error_out: |
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return fid; |
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}
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