VFS: Put a small type field into struct dentry::d_flags
Put a type field into struct dentry::d_flags to indicate if the dentry is one
of the following types that relate particularly to pathwalk:
Miss (negative dentry)
Directory
"Automount" directory (defective - no i_op->lookup())
Symlink
Other (regular, socket, fifo, device)
The type field is set to one of the first five types on a dentry by calls to
__d_instantiate() and d_obtain_alias() from information in the inode (if one is
given).
The type is cleared by dentry_unlink_inode() when it reconstitutes an existing
dentry as a negative dentry.
Accessors provided are:
d_set_type(dentry, type)
d_is_directory(dentry)
d_is_autodir(dentry)
d_is_symlink(dentry)
d_is_file(dentry)
d_is_negative(dentry)
d_is_positive(dentry)
A bunch of checks in pathname resolution switched to those.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/dcache.c b/fs/dcache.c
index fb7bcf3..525770e 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -343,6 +343,7 @@
__releases(dentry->d_inode->i_lock)
{
struct inode *inode = dentry->d_inode;
+ __d_clear_type(dentry);
dentry->d_inode = NULL;
hlist_del_init(&dentry->d_alias);
dentry_rcuwalk_barrier(dentry);
@@ -1648,14 +1649,42 @@
}
EXPORT_SYMBOL(d_set_d_op);
+static unsigned d_flags_for_inode(struct inode *inode)
+{
+ unsigned add_flags = DCACHE_FILE_TYPE;
+
+ if (!inode)
+ return DCACHE_MISS_TYPE;
+
+ if (S_ISDIR(inode->i_mode)) {
+ add_flags = DCACHE_DIRECTORY_TYPE;
+ if (unlikely(!(inode->i_opflags & IOP_LOOKUP))) {
+ if (unlikely(!inode->i_op->lookup))
+ add_flags = DCACHE_AUTODIR_TYPE;
+ else
+ inode->i_opflags |= IOP_LOOKUP;
+ }
+ } else if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) {
+ if (unlikely(inode->i_op->follow_link))
+ add_flags = DCACHE_SYMLINK_TYPE;
+ else
+ inode->i_opflags |= IOP_NOFOLLOW;
+ }
+
+ if (unlikely(IS_AUTOMOUNT(inode)))
+ add_flags |= DCACHE_NEED_AUTOMOUNT;
+ return add_flags;
+}
+
static void __d_instantiate(struct dentry *dentry, struct inode *inode)
{
+ unsigned add_flags = d_flags_for_inode(inode);
+
spin_lock(&dentry->d_lock);
- if (inode) {
- if (unlikely(IS_AUTOMOUNT(inode)))
- dentry->d_flags |= DCACHE_NEED_AUTOMOUNT;
+ dentry->d_flags &= ~DCACHE_ENTRY_TYPE;
+ dentry->d_flags |= add_flags;
+ if (inode)
hlist_add_head(&dentry->d_alias, &inode->i_dentry);
- }
dentry->d_inode = inode;
dentry_rcuwalk_barrier(dentry);
spin_unlock(&dentry->d_lock);
@@ -1860,6 +1889,7 @@
static const struct qstr anonstring = QSTR_INIT("/", 1);
struct dentry *tmp;
struct dentry *res;
+ unsigned add_flags;
if (!inode)
return ERR_PTR(-ESTALE);
@@ -1885,9 +1915,11 @@
}
/* attach a disconnected dentry */
+ add_flags = d_flags_for_inode(inode) | DCACHE_DISCONNECTED;
+
spin_lock(&tmp->d_lock);
tmp->d_inode = inode;
- tmp->d_flags |= DCACHE_DISCONNECTED;
+ tmp->d_flags |= add_flags;
hlist_add_head(&tmp->d_alias, &inode->i_dentry);
hlist_bl_lock(&tmp->d_sb->s_anon);
hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon);
diff --git a/fs/namei.c b/fs/namei.c
index e5c0118..e1fa433 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1501,18 +1501,9 @@
* so we keep a cache of "no, this doesn't need follow_link"
* for the common case.
*/
-static inline int should_follow_link(struct inode *inode, int follow)
+static inline int should_follow_link(struct dentry *dentry, int follow)
{
- if (unlikely(!(inode->i_opflags & IOP_NOFOLLOW))) {
- if (likely(inode->i_op->follow_link))
- return follow;
-
- /* This gets set once for the inode lifetime */
- spin_lock(&inode->i_lock);
- inode->i_opflags |= IOP_NOFOLLOW;
- spin_unlock(&inode->i_lock);
- }
- return 0;
+ return unlikely(d_is_symlink(dentry)) ? follow : 0;
}
static inline int walk_component(struct nameidata *nd, struct path *path,
@@ -1542,7 +1533,7 @@
if (!inode)
goto out_path_put;
- if (should_follow_link(inode, follow)) {
+ if (should_follow_link(path->dentry, follow)) {
if (nd->flags & LOOKUP_RCU) {
if (unlikely(unlazy_walk(nd, path->dentry))) {
err = -ECHILD;
@@ -1601,26 +1592,6 @@
}
/*
- * We really don't want to look at inode->i_op->lookup
- * when we don't have to. So we keep a cache bit in
- * the inode ->i_opflags field that says "yes, we can
- * do lookup on this inode".
- */
-static inline int can_lookup(struct inode *inode)
-{
- if (likely(inode->i_opflags & IOP_LOOKUP))
- return 1;
- if (likely(!inode->i_op->lookup))
- return 0;
-
- /* We do this once for the lifetime of the inode */
- spin_lock(&inode->i_lock);
- inode->i_opflags |= IOP_LOOKUP;
- spin_unlock(&inode->i_lock);
- return 1;
-}
-
-/*
* We can do the critical dentry name comparison and hashing
* operations one word at a time, but we are limited to:
*
@@ -1823,7 +1794,7 @@
if (err)
return err;
}
- if (!can_lookup(nd->inode)) {
+ if (!d_is_directory(nd->path.dentry)) {
err = -ENOTDIR;
break;
}
@@ -1841,9 +1812,10 @@
nd->flags = flags | LOOKUP_JUMPED;
nd->depth = 0;
if (flags & LOOKUP_ROOT) {
- struct inode *inode = nd->root.dentry->d_inode;
+ struct dentry *root = nd->root.dentry;
+ struct inode *inode = root->d_inode;
if (*name) {
- if (!can_lookup(inode))
+ if (!d_is_directory(root))
return -ENOTDIR;
retval = inode_permission(inode, MAY_EXEC);
if (retval)
@@ -1899,7 +1871,7 @@
dentry = f.file->f_path.dentry;
if (*name) {
- if (!can_lookup(dentry->d_inode)) {
+ if (!d_is_directory(dentry)) {
fdput(f);
return -ENOTDIR;
}
@@ -1981,7 +1953,7 @@
err = complete_walk(nd);
if (!err && nd->flags & LOOKUP_DIRECTORY) {
- if (!can_lookup(nd->inode)) {
+ if (!d_is_directory(nd->path.dentry)) {
path_put(&nd->path);
err = -ENOTDIR;
}
@@ -2273,7 +2245,7 @@
}
path->dentry = dentry;
path->mnt = mntget(nd->path.mnt);
- if (should_follow_link(dentry->d_inode, nd->flags & LOOKUP_FOLLOW))
+ if (should_follow_link(dentry, nd->flags & LOOKUP_FOLLOW))
return 1;
follow_mount(path);
error = 0;
@@ -2417,12 +2389,14 @@
* 10. We don't allow removal of NFS sillyrenamed files; it's handled by
* nfs_async_unlink().
*/
-static int may_delete(struct inode *dir,struct dentry *victim,int isdir)
+static int may_delete(struct inode *dir, struct dentry *victim, bool isdir)
{
+ struct inode *inode = victim->d_inode;
int error;
- if (!victim->d_inode)
+ if (d_is_negative(victim))
return -ENOENT;
+ BUG_ON(!inode);
BUG_ON(victim->d_parent->d_inode != dir);
audit_inode_child(dir, victim, AUDIT_TYPE_CHILD_DELETE);
@@ -2432,15 +2406,16 @@
return error;
if (IS_APPEND(dir))
return -EPERM;
- if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)||
- IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode))
+
+ if (check_sticky(dir, inode) || IS_APPEND(inode) ||
+ IS_IMMUTABLE(inode) || IS_SWAPFILE(inode))
return -EPERM;
if (isdir) {
- if (!S_ISDIR(victim->d_inode->i_mode))
+ if (!d_is_directory(victim) && !d_is_autodir(victim))
return -ENOTDIR;
if (IS_ROOT(victim))
return -EBUSY;
- } else if (S_ISDIR(victim->d_inode->i_mode))
+ } else if (d_is_directory(victim) || d_is_autodir(victim))
return -EISDIR;
if (IS_DEADDIR(dir))
return -ENOENT;
@@ -2974,7 +2949,7 @@
/*
* create/update audit record if it already exists.
*/
- if (path->dentry->d_inode)
+ if (d_is_positive(path->dentry))
audit_inode(name, path->dentry, 0);
/*
@@ -3003,12 +2978,12 @@
finish_lookup:
/* we _can_ be in RCU mode here */
error = -ENOENT;
- if (!inode) {
+ if (d_is_negative(path->dentry)) {
path_to_nameidata(path, nd);
goto out;
}
- if (should_follow_link(inode, !symlink_ok)) {
+ if (should_follow_link(path->dentry, !symlink_ok)) {
if (nd->flags & LOOKUP_RCU) {
if (unlikely(unlazy_walk(nd, path->dentry))) {
error = -ECHILD;
@@ -3037,10 +3012,11 @@
}
audit_inode(name, nd->path.dentry, 0);
error = -EISDIR;
- if ((open_flag & O_CREAT) && S_ISDIR(nd->inode->i_mode))
+ if ((open_flag & O_CREAT) &&
+ (d_is_directory(nd->path.dentry) || d_is_autodir(nd->path.dentry)))
goto out;
error = -ENOTDIR;
- if ((nd->flags & LOOKUP_DIRECTORY) && !can_lookup(nd->inode))
+ if ((nd->flags & LOOKUP_DIRECTORY) && !d_is_directory(nd->path.dentry))
goto out;
if (!S_ISREG(nd->inode->i_mode))
will_truncate = false;
@@ -3266,7 +3242,7 @@
nd.root.mnt = mnt;
nd.root.dentry = dentry;
- if (dentry->d_inode->i_op->follow_link && op->intent & LOOKUP_OPEN)
+ if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN)
return ERR_PTR(-ELOOP);
file = path_openat(-1, &filename, &nd, op, flags | LOOKUP_RCU);
@@ -3316,8 +3292,9 @@
goto unlock;
error = -EEXIST;
- if (dentry->d_inode)
+ if (d_is_positive(dentry))
goto fail;
+
/*
* Special case - lookup gave negative, but... we had foo/bar/
* From the vfs_mknod() POV we just have a negative dentry -
@@ -3706,7 +3683,7 @@
if (nd.last.name[nd.last.len])
goto slashes;
inode = dentry->d_inode;
- if (!inode)
+ if (d_is_negative(dentry))
goto slashes;
ihold(inode);
error = security_path_unlink(&nd.path, dentry);
@@ -3731,8 +3708,12 @@
return error;
slashes:
- error = !dentry->d_inode ? -ENOENT :
- S_ISDIR(dentry->d_inode->i_mode) ? -EISDIR : -ENOTDIR;
+ if (d_is_negative(dentry))
+ error = -ENOENT;
+ else if (d_is_directory(dentry) || d_is_autodir(dentry))
+ error = -EISDIR;
+ else
+ error = -ENOTDIR;
goto exit2;
}
@@ -4046,7 +4027,7 @@
struct inode *new_dir, struct dentry *new_dentry)
{
int error;
- int is_dir = S_ISDIR(old_dentry->d_inode->i_mode);
+ int is_dir = d_is_directory(old_dentry) || d_is_autodir(old_dentry);
const unsigned char *old_name;
if (old_dentry->d_inode == new_dentry->d_inode)
@@ -4134,10 +4115,10 @@
goto exit3;
/* source must exist */
error = -ENOENT;
- if (!old_dentry->d_inode)
+ if (d_is_negative(old_dentry))
goto exit4;
/* unless the source is a directory trailing slashes give -ENOTDIR */
- if (!S_ISDIR(old_dentry->d_inode->i_mode)) {
+ if (!d_is_directory(old_dentry) && !d_is_autodir(old_dentry)) {
error = -ENOTDIR;
if (oldnd.last.name[oldnd.last.len])
goto exit4;