summaryrefslogtreecommitdiffstats
path: root/fs/dcache.c
diff options
context:
space:
mode:
Diffstat (limited to 'fs/dcache.c')
-rw-r--r--fs/dcache.c83
1 files changed, 36 insertions, 47 deletions
diff --git a/fs/dcache.c b/fs/dcache.c
index be18598c7fd7..a88948b8bd17 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -301,6 +301,27 @@ static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent)
return parent;
}
+/*
+ * Unhash a dentry without inserting an RCU walk barrier or checking that
+ * dentry->d_lock is locked. The caller must take care of that, if
+ * appropriate.
+ */
+static void __d_shrink(struct dentry *dentry)
+{
+ if (!d_unhashed(dentry)) {
+ struct hlist_bl_head *b;
+ if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED))
+ b = &dentry->d_sb->s_anon;
+ else
+ b = d_hash(dentry->d_parent, dentry->d_name.hash);
+
+ hlist_bl_lock(b);
+ __hlist_bl_del(&dentry->d_hash);
+ dentry->d_hash.pprev = NULL;
+ hlist_bl_unlock(b);
+ }
+}
+
/**
* d_drop - drop a dentry
* @dentry: dentry to drop
@@ -319,17 +340,7 @@ static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent)
void __d_drop(struct dentry *dentry)
{
if (!d_unhashed(dentry)) {
- struct hlist_bl_head *b;
- if (unlikely(dentry->d_flags & DCACHE_DISCONNECTED))
- b = &dentry->d_sb->s_anon;
- else
- b = d_hash(dentry->d_parent, dentry->d_name.hash);
-
- hlist_bl_lock(b);
- __hlist_bl_del(&dentry->d_hash);
- dentry->d_hash.pprev = NULL;
- hlist_bl_unlock(b);
-
+ __d_shrink(dentry);
dentry_rcuwalk_barrier(dentry);
}
}
@@ -784,6 +795,7 @@ relock:
/**
* prune_dcache_sb - shrink the dcache
+ * @sb: superblock
* @nr_to_scan: number of entries to try to free
*
* Attempt to shrink the superblock dcache LRU by @nr_to_scan entries. This is
@@ -828,44 +840,24 @@ EXPORT_SYMBOL(shrink_dcache_sb);
static void shrink_dcache_for_umount_subtree(struct dentry *dentry)
{
struct dentry *parent;
- unsigned detached = 0;
BUG_ON(!IS_ROOT(dentry));
- /* detach this root from the system */
- spin_lock(&dentry->d_lock);
- dentry_lru_del(dentry);
- __d_drop(dentry);
- spin_unlock(&dentry->d_lock);
-
for (;;) {
/* descend to the first leaf in the current subtree */
- while (!list_empty(&dentry->d_subdirs)) {
- struct dentry *loop;
-
- /* this is a branch with children - detach all of them
- * from the system in one go */
- spin_lock(&dentry->d_lock);
- list_for_each_entry(loop, &dentry->d_subdirs,
- d_u.d_child) {
- spin_lock_nested(&loop->d_lock,
- DENTRY_D_LOCK_NESTED);
- dentry_lru_del(loop);
- __d_drop(loop);
- spin_unlock(&loop->d_lock);
- }
- spin_unlock(&dentry->d_lock);
-
- /* move to the first child */
+ while (!list_empty(&dentry->d_subdirs))
dentry = list_entry(dentry->d_subdirs.next,
struct dentry, d_u.d_child);
- }
/* consume the dentries from this leaf up through its parents
* until we find one with children or run out altogether */
do {
struct inode *inode;
+ /* detach from the system */
+ dentry_lru_del(dentry);
+ __d_shrink(dentry);
+
if (dentry->d_count != 0) {
printk(KERN_ERR
"BUG: Dentry %p{i=%lx,n=%s}"
@@ -886,14 +878,10 @@ static void shrink_dcache_for_umount_subtree(struct dentry *dentry)
list_del(&dentry->d_u.d_child);
} else {
parent = dentry->d_parent;
- spin_lock(&parent->d_lock);
parent->d_count--;
list_del(&dentry->d_u.d_child);
- spin_unlock(&parent->d_lock);
}
- detached++;
-
inode = dentry->d_inode;
if (inode) {
dentry->d_inode = NULL;
@@ -938,9 +926,7 @@ void shrink_dcache_for_umount(struct super_block *sb)
dentry = sb->s_root;
sb->s_root = NULL;
- spin_lock(&dentry->d_lock);
dentry->d_count--;
- spin_unlock(&dentry->d_lock);
shrink_dcache_for_umount_subtree(dentry);
while (!hlist_bl_empty(&sb->s_anon)) {
@@ -1743,7 +1729,7 @@ seqretry:
*/
if (read_seqcount_retry(&dentry->d_seq, *seq))
goto seqretry;
- if (parent->d_flags & DCACHE_OP_COMPARE) {
+ if (unlikely(parent->d_flags & DCACHE_OP_COMPARE)) {
if (parent->d_op->d_compare(parent, *inode,
dentry, i,
tlen, tname, name))
@@ -2138,8 +2124,9 @@ static void dentry_unlock_parents_for_move(struct dentry *dentry,
* @target: new dentry
*
* Update the dcache to reflect the move of a file name. Negative
- * dcache entries should not be moved in this way. Caller hold
- * rename_lock.
+ * dcache entries should not be moved in this way. Caller must hold
+ * rename_lock, the i_mutex of the source and target directories,
+ * and the sb->s_vfs_rename_mutex if they differ. See lock_rename().
*/
static void __d_move(struct dentry * dentry, struct dentry * target)
{
@@ -2202,7 +2189,8 @@ static void __d_move(struct dentry * dentry, struct dentry * target)
* @target: new dentry
*
* Update the dcache to reflect the move of a file name. Negative
- * dcache entries should not be moved in this way.
+ * dcache entries should not be moved in this way. See the locking
+ * requirements for __d_move.
*/
void d_move(struct dentry *dentry, struct dentry *target)
{
@@ -2320,7 +2308,8 @@ static void __d_materialise_dentry(struct dentry *dentry, struct dentry *anon)
* @inode: inode to bind to the dentry, to which aliases may be attached
*
* Introduces an dentry into the tree, substituting an extant disconnected
- * root directory alias in its place if there is one
+ * root directory alias in its place if there is one. Caller must hold the
+ * i_mutex of the parent directory.
*/
struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
{