mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
synced 2025-01-06 14:05:39 +00:00
untangle the "need_reval_dot" mess
instead of ad-hackery around need_reval_dot(), do the following: set a flag (LOOKUP_JUMPED) in the beginning of path, on absolute symlink traversal, on ".." and on procfs-style symlinks. Clear on normal components, leave unchanged on ".". Non-nested callers of link_path_walk() call handle_reval_path(), which checks that flag is set and that fs does want the final revalidate thing, then does ->d_revalidate(). In link_path_walk() all the return_reval stuff is gone. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro
parent
fe479a580d
commit
16c2cd7179
107
fs/namei.c
107
fs/namei.c
@ -613,19 +613,8 @@ do_revalidate_rcu(struct dentry *dentry, struct nameidata *nd)
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return dentry;
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}
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static inline int need_reval_dot(struct dentry *dentry)
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{
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if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE)))
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return 0;
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if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)))
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return 0;
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return 1;
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}
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/*
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* force_reval_path - force revalidation of a dentry
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* handle_reval_path - force revalidation of a dentry
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*
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* In some situations the path walking code will trust dentries without
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* revalidating them. This causes problems for filesystems that depend on
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@ -639,27 +628,28 @@ static inline int need_reval_dot(struct dentry *dentry)
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* invalidate the dentry. It's up to the caller to handle putting references
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* to the path if necessary.
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*/
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static int
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force_reval_path(struct path *path, struct nameidata *nd)
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static inline int handle_reval_path(struct nameidata *nd)
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{
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struct dentry *dentry = nd->path.dentry;
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int status;
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struct dentry *dentry = path->dentry;
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/*
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* only check on filesystems where it's possible for the dentry to
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* become stale.
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*/
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if (!need_reval_dot(dentry))
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if (likely(!(nd->flags & LOOKUP_JUMPED)))
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return 0;
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if (likely(!(dentry->d_flags & DCACHE_OP_REVALIDATE)))
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return 0;
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if (likely(!(dentry->d_sb->s_type->fs_flags & FS_REVAL_DOT)))
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return 0;
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/* Note: we do not d_invalidate() */
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status = d_revalidate(dentry, nd);
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if (status > 0)
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return 0;
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if (!status) {
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d_invalidate(dentry);
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if (!status)
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status = -ESTALE;
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}
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return status;
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}
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@ -728,6 +718,7 @@ static __always_inline int __vfs_follow_link(struct nameidata *nd, const char *l
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path_put(&nd->path);
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nd->path = nd->root;
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path_get(&nd->root);
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nd->flags |= LOOKUP_JUMPED;
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}
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nd->inode = nd->path.dentry->d_inode;
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@ -779,11 +770,8 @@ __do_follow_link(const struct path *link, struct nameidata *nd, void **p)
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error = 0;
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if (s)
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error = __vfs_follow_link(nd, s);
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else if (nd->last_type == LAST_BIND) {
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error = force_reval_path(&nd->path, nd);
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if (error)
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path_put(&nd->path);
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}
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else if (nd->last_type == LAST_BIND)
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nd->flags |= LOOKUP_JUMPED;
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}
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return error;
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}
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@ -1351,7 +1339,7 @@ static int link_path_walk(const char *name, struct nameidata *nd)
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while (*name=='/')
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name++;
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if (!*name)
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goto return_reval;
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goto return_base;
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if (nd->depth)
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lookup_flags = LOOKUP_FOLLOW | (nd->flags & LOOKUP_CONTINUE);
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@ -1385,12 +1373,16 @@ static int link_path_walk(const char *name, struct nameidata *nd)
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type = LAST_NORM;
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if (this.name[0] == '.') switch (this.len) {
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case 2:
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if (this.name[1] == '.')
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if (this.name[1] == '.') {
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type = LAST_DOTDOT;
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nd->flags |= LOOKUP_JUMPED;
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}
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break;
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case 1:
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type = LAST_DOT;
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}
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if (likely(type == LAST_NORM))
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nd->flags &= ~LOOKUP_JUMPED;
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/* remove trailing slashes? */
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if (!c)
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@ -1456,7 +1448,7 @@ static int link_path_walk(const char *name, struct nameidata *nd)
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} else
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follow_dotdot(nd);
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}
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goto return_reval;
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goto return_base;
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}
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err = do_lookup(nd, &this, &next, &inode);
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if (err)
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@ -1483,24 +1475,6 @@ static int link_path_walk(const char *name, struct nameidata *nd)
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lookup_parent:
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nd->last = this;
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nd->last_type = type;
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if (type == LAST_NORM)
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goto return_base;
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return_reval:
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/*
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* We bypassed the ordinary revalidation routines.
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* We may need to check the cached dentry for staleness.
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*/
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if (need_reval_dot(nd->path.dentry)) {
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if (nameidata_drop_rcu_last_maybe(nd))
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return -ECHILD;
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/* Note: we do not d_invalidate() */
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err = d_revalidate(nd->path.dentry, nd);
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if (!err)
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err = -ESTALE;
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if (err < 0)
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break;
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return 0;
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}
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return_base:
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if (nameidata_drop_rcu_last_maybe(nd))
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return -ECHILD;
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@ -1523,7 +1497,7 @@ static int path_init(int dfd, const char *name, unsigned int flags, struct namei
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struct file *file;
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nd->last_type = LAST_ROOT; /* if there are only slashes... */
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nd->flags = flags;
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nd->flags = flags | LOOKUP_JUMPED;
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nd->depth = 0;
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nd->root.mnt = NULL;
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nd->file = NULL;
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@ -1630,6 +1604,9 @@ static int path_lookupat(int dfd, const char *name,
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br_read_unlock(vfsmount_lock);
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}
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if (!retval)
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retval = handle_reval_path(nd);
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if (nd->file) {
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fput(nd->file);
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nd->file = NULL;
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@ -1690,7 +1667,7 @@ int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
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/* same as do_path_lookup */
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nd->last_type = LAST_ROOT;
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nd->flags = flags;
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nd->flags = flags | LOOKUP_JUMPED;
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nd->depth = 0;
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nd->path.dentry = dentry;
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@ -1703,6 +1680,8 @@ int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
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current->total_link_count = 0;
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result = link_path_walk(name, nd);
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if (!result)
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result = handle_reval_path(nd);
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if (result == -ESTALE) {
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/* nd->path had been dropped */
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current->total_link_count = 0;
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@ -1710,8 +1689,11 @@ int vfs_path_lookup(struct dentry *dentry, struct vfsmount *mnt,
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nd->path.mnt = mnt;
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nd->inode = dentry->d_inode;
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path_get(&nd->path);
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nd->flags |= LOOKUP_REVAL;
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nd->flags = flags | LOOKUP_JUMPED | LOOKUP_REVAL;
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result = link_path_walk(name, nd);
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if (!result)
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result = handle_reval_path(nd);
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}
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if (unlikely(!result && !audit_dummy_context() && nd->path.dentry &&
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nd->inode))
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@ -2198,30 +2180,29 @@ static struct file *do_last(struct nameidata *nd, struct path *path,
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{
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struct dentry *dir = nd->path.dentry;
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struct file *filp;
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int error = -EISDIR;
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int error;
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switch (nd->last_type) {
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case LAST_DOTDOT:
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follow_dotdot(nd);
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dir = nd->path.dentry;
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case LAST_DOT:
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if (need_reval_dot(dir)) {
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int status = d_revalidate(nd->path.dentry, nd);
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if (!status)
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status = -ESTALE;
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if (status < 0) {
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error = status;
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goto exit;
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}
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}
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/* fallthrough */
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case LAST_ROOT:
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error = handle_reval_path(nd);
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if (error)
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goto exit;
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error = -EISDIR;
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goto exit;
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case LAST_BIND:
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error = handle_reval_path(nd);
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if (error)
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goto exit;
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audit_inode(pathname, dir);
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goto ok;
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}
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error = -EISDIR;
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/* trailing slashes? */
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if (nd->last.name[nd->last.len])
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goto exit;
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@ -2422,7 +2403,7 @@ struct file *do_filp_open(int dfd, const char *pathname,
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/*
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* We have the parent and last component.
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*/
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nd.flags = flags;
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nd.flags = (nd.flags & ~LOOKUP_PARENT) | flags;
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filp = do_last(&nd, &path, open_flag, acc_mode, mode, pathname);
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while (unlikely(!filp)) { /* trailing symlink */
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struct path link = path;
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@ -63,6 +63,8 @@ enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT, LAST_BIND};
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#define LOOKUP_EXCL 0x0400
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#define LOOKUP_RENAME_TARGET 0x0800
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#define LOOKUP_JUMPED 0x1000
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extern int user_path_at(int, const char __user *, unsigned, struct path *);
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#define user_path(name, path) user_path_at(AT_FDCWD, name, LOOKUP_FOLLOW, path)
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