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authorNick Piggin <npiggin@kernel.dk>2011-01-07 09:49:34 +0300
committerNick Piggin <npiggin@kernel.dk>2011-01-07 09:50:21 +0300
commit2fd6b7f50797f2e993eea59e0a0b8c6399c811dc (patch)
treece33b94b34844c09103836cf4cfa4364b742f217 /fs/autofs4/root.c
parentda5029563a0a026c64821b09e8e7b4fd81d3fe1b (diff)
downloadlinux-2fd6b7f50797f2e993eea59e0a0b8c6399c811dc.tar.xz
fs: dcache scale subdirs
Protect d_subdirs and d_child with d_lock, except in filesystems that aren't using dcache_lock for these anyway (eg. using i_mutex). Note: if we change the locking rule in future so that ->d_child protection is provided only with ->d_parent->d_lock, it may allow us to reduce some locking. But it would be an exception to an otherwise regular locking scheme, so we'd have to see some good results. Probably not worthwhile. Signed-off-by: Nick Piggin <npiggin@kernel.dk>
Diffstat (limited to 'fs/autofs4/root.c')
-rw-r--r--fs/autofs4/root.c18
1 files changed, 16 insertions, 2 deletions
diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c
index 7922509b5b2b..7a9ed6b88291 100644
--- a/fs/autofs4/root.c
+++ b/fs/autofs4/root.c
@@ -143,10 +143,13 @@ static int autofs4_dir_open(struct inode *inode, struct file *file)
* it.
*/
spin_lock(&dcache_lock);
+ spin_lock(&dentry->d_lock);
if (!d_mountpoint(dentry) && list_empty(&dentry->d_subdirs)) {
+ spin_unlock(&dentry->d_lock);
spin_unlock(&dcache_lock);
return -ENOENT;
}
+ spin_unlock(&dentry->d_lock);
spin_unlock(&dcache_lock);
out:
@@ -253,7 +256,9 @@ static void *autofs4_follow_link(struct dentry *dentry, struct nameidata *nd)
lookup_type = autofs4_need_mount(nd->flags);
spin_lock(&sbi->fs_lock);
spin_lock(&dcache_lock);
+ spin_lock(&dentry->d_lock);
if (!(lookup_type || ino->flags & AUTOFS_INF_PENDING)) {
+ spin_unlock(&dentry->d_lock);
spin_unlock(&dcache_lock);
spin_unlock(&sbi->fs_lock);
goto follow;
@@ -266,6 +271,7 @@ static void *autofs4_follow_link(struct dentry *dentry, struct nameidata *nd)
*/
if (ino->flags & AUTOFS_INF_PENDING ||
(!d_mountpoint(dentry) && list_empty(&dentry->d_subdirs))) {
+ spin_unlock(&dentry->d_lock);
spin_unlock(&dcache_lock);
spin_unlock(&sbi->fs_lock);
@@ -275,6 +281,7 @@ static void *autofs4_follow_link(struct dentry *dentry, struct nameidata *nd)
goto follow;
}
+ spin_unlock(&dentry->d_lock);
spin_unlock(&dcache_lock);
spin_unlock(&sbi->fs_lock);
follow:
@@ -347,10 +354,12 @@ static int autofs4_revalidate(struct dentry *dentry, struct nameidata *nd)
/* Check for a non-mountpoint directory with no contents */
spin_lock(&dcache_lock);
+ spin_lock(&dentry->d_lock);
if (S_ISDIR(dentry->d_inode->i_mode) &&
!d_mountpoint(dentry) && list_empty(&dentry->d_subdirs)) {
DPRINTK("dentry=%p %.*s, emptydir",
dentry, dentry->d_name.len, dentry->d_name.name);
+ spin_unlock(&dentry->d_lock);
spin_unlock(&dcache_lock);
/* The daemon never causes a mount to trigger */
@@ -367,6 +376,7 @@ static int autofs4_revalidate(struct dentry *dentry, struct nameidata *nd)
return status;
}
+ spin_unlock(&dentry->d_lock);
spin_unlock(&dcache_lock);
return 1;
@@ -776,12 +786,16 @@ static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
return -EACCES;
spin_lock(&dcache_lock);
+ spin_lock(&sbi->lookup_lock);
+ spin_lock(&dentry->d_lock);
if (!list_empty(&dentry->d_subdirs)) {
+ spin_unlock(&dentry->d_lock);
+ spin_unlock(&sbi->lookup_lock);
spin_unlock(&dcache_lock);
return -ENOTEMPTY;
}
- autofs4_add_expiring(dentry);
- spin_lock(&dentry->d_lock);
+ __autofs4_add_expiring(dentry);
+ spin_unlock(&sbi->lookup_lock);
__d_drop(dentry);
spin_unlock(&dentry->d_lock);
spin_unlock(&dcache_lock);