[PATCH 45/46] fs: dcache per-inode inode alias locking

From: Nick Piggin
Date: Sat Nov 27 2010 - 05:30:26 EST

dcache_inode_lock can be replaced with per-inode locking. Use existing
inode->i_lock for this. This is slightly non-trivial because we sometimes
need to find the inode from the dentry, which requires d_inode to be
stabilised (either with refcount or d_lock).

Signed-off-by: Nick Piggin <npiggin@xxxxxxxxx>
---
fs/9p/vfs_inode.c | 4 +-
fs/affs/amigaffs.c | 4 +-
fs/dcache.c | 84 +++++++++++++++++++++++++----------------------
fs/exportfs/expfs.c | 12 ++++---
fs/nfs/getroot.c | 4 +-
fs/notify/fsnotify.c | 4 +-
fs/ocfs2/dcache.c | 4 +-
include/linux/dcache.h | 1 -
8 files changed, 62 insertions(+), 55 deletions(-)

diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index df8bbb3..5978298 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -277,11 +277,11 @@ static struct dentry *v9fs_dentry_from_dir_inode(struct inode *inode)
{
struct dentry *dentry;

- spin_lock(&dcache_inode_lock);
+ spin_lock(&inode->i_lock);
/* Directory should have only one entry. */
BUG_ON(S_ISDIR(inode->i_mode) && !list_is_singular(&inode->i_dentry));
dentry = list_entry(inode->i_dentry.next, struct dentry, d_alias);
- spin_unlock(&dcache_inode_lock);
+ spin_unlock(&inode->i_lock);
return dentry;
}

diff --git a/fs/affs/amigaffs.c b/fs/affs/amigaffs.c
index 600101a..3a4557e 100644
--- a/fs/affs/amigaffs.c
+++ b/fs/affs/amigaffs.c
@@ -128,7 +128,7 @@ affs_fix_dcache(struct dentry *dentry, u32 entry_ino)
void *data = dentry->d_fsdata;
struct list_head *head, *next;

- spin_lock(&dcache_inode_lock);
+ spin_lock(&inode->i_lock);
head = &inode->i_dentry;
next = head->next;
while (next != head) {
@@ -139,7 +139,7 @@ affs_fix_dcache(struct dentry *dentry, u32 entry_ino)
}
next = next->next;
}
- spin_unlock(&dcache_inode_lock);
+ spin_unlock(&inode->i_lock);
}


diff --git a/fs/dcache.c b/fs/dcache.c
index 5e19940..809ec46 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -39,8 +39,8 @@

/*
* Usage:
- * dcache_inode_lock protects:
- * - i_dentry, d_alias, d_inode
+ * dcache->d_inode->i_lock protects:
+ * - i_dentry, d_alias, d_inode of aliases
* dcache_hash_bucket lock protects:
* - the dcache hash table
* dcache_lru_lock protects:
@@ -56,7 +56,7 @@
* - d_alias, d_inode
*
* Ordering:
- * dcache_inode_lock
+ * dentry->d_inode->i_lock
* dentry->d_lock
* dcache_lru_lock
* dcache_hash_bucket lock
@@ -75,12 +75,10 @@
int sysctl_vfs_cache_pressure __read_mostly = 100;
EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure);

-__cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_inode_lock);
static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lru_lock);
__cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock);

EXPORT_SYMBOL(rename_lock);
-EXPORT_SYMBOL(dcache_inode_lock);

static struct kmem_cache *dentry_cache __read_mostly;

@@ -172,7 +170,7 @@ static void d_free(struct dentry *dentry)
*/
static void dentry_iput(struct dentry * dentry)
__releases(dentry->d_lock)
- __releases(dcache_inode_lock)
+ __releases(dentry->d_inode->i_lock)
{
struct inode *inode = dentry->d_inode;
if (inode) {
@@ -181,7 +179,7 @@ static void dentry_iput(struct dentry * dentry)
write_seqcount_end(&dentry->d_seq);
list_del_init(&dentry->d_alias);
spin_unlock(&dentry->d_lock);
- spin_unlock(&dcache_inode_lock);
+ spin_unlock(&inode->i_lock);
if (!inode->i_nlink)
fsnotify_inoderemove(inode);
if (dentry->d_op && dentry->d_op->d_iput)
@@ -190,7 +188,6 @@ static void dentry_iput(struct dentry * dentry)
iput(inode);
} else {
spin_unlock(&dentry->d_lock);
- spin_unlock(&dcache_inode_lock);
}
}

@@ -251,7 +248,7 @@ static void dentry_lru_move_tail(struct dentry *dentry)
static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent)
__releases(dentry->d_lock)
__releases(parent->d_lock)
- __releases(dcache_inode_lock)
+ __releases(dentry->d_inode->i_lock)
{
dentry->d_parent = NULL;
list_del(&dentry->d_u.d_child);
@@ -275,9 +272,11 @@ static struct dentry *d_kill(struct dentry *dentry, struct dentry *parent)
static inline struct dentry *dentry_kill(struct dentry *dentry, int ref)
__releases(dentry->d_lock)
{
+ struct inode *inode;
struct dentry *parent;

- if (!spin_trylock(&dcache_inode_lock)) {
+ inode = dentry->d_inode;
+ if (inode && !spin_trylock(&inode->i_lock)) {
relock:
spin_unlock(&dentry->d_lock);
cpu_relax();
@@ -288,7 +287,8 @@ relock:
else
parent = dentry->d_parent;
if (parent && !spin_trylock(&parent->d_lock)) {
- spin_unlock(&dcache_inode_lock);
+ if (inode)
+ spin_unlock(&inode->i_lock);
goto relock;
}
if (ref)
@@ -560,9 +560,9 @@ struct dentry *d_find_alias(struct inode *inode)
struct dentry *de = NULL;

if (!list_empty(&inode->i_dentry)) {
- spin_lock(&dcache_inode_lock);
+ spin_lock(&inode->i_lock);
de = __d_find_alias(inode, 0);
- spin_unlock(&dcache_inode_lock);
+ spin_unlock(&inode->i_lock);
}
return de;
}
@@ -576,20 +576,20 @@ void d_prune_aliases(struct inode *inode)
{
struct dentry *dentry;
restart:
- spin_lock(&dcache_inode_lock);
+ spin_lock(&inode->i_lock);
list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
spin_lock(&dentry->d_lock);
if (!dentry->d_count) {
__dget_dlock(dentry);
__d_drop(dentry);
spin_unlock(&dentry->d_lock);
- spin_unlock(&dcache_inode_lock);
+ spin_unlock(&inode->i_lock);
dput(dentry);
goto restart;
}
spin_unlock(&dentry->d_lock);
}
- spin_unlock(&dcache_inode_lock);
+ spin_unlock(&inode->i_lock);
}
EXPORT_SYMBOL(d_prune_aliases);

@@ -1334,9 +1334,11 @@ static void __d_instantiate(struct dentry *dentry, struct inode *inode)
void d_instantiate(struct dentry *entry, struct inode * inode)
{
BUG_ON(!list_empty(&entry->d_alias));
- spin_lock(&dcache_inode_lock);
+ if (inode)
+ spin_lock(&inode->i_lock);
__d_instantiate(entry, inode);
- spin_unlock(&dcache_inode_lock);
+ if (inode)
+ spin_unlock(&inode->i_lock);
security_d_instantiate(entry, inode);
}
EXPORT_SYMBOL(d_instantiate);
@@ -1399,9 +1401,11 @@ struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode)

BUG_ON(!list_empty(&entry->d_alias));

- spin_lock(&dcache_inode_lock);
+ if (inode)
+ spin_lock(&inode->i_lock);
result = __d_instantiate_unique(entry, inode);
- spin_unlock(&dcache_inode_lock);
+ if (inode)
+ spin_unlock(&inode->i_lock);

if (!result) {
security_d_instantiate(entry, inode);
@@ -1483,10 +1487,10 @@ struct dentry *d_obtain_alias(struct inode *inode)
tmp->d_parent = tmp; /* make sure dput doesn't croak */


- spin_lock(&dcache_inode_lock);
+ spin_lock(&inode->i_lock);
res = __d_find_alias(inode, 0);
if (res) {
- spin_unlock(&dcache_inode_lock);
+ spin_unlock(&inode->i_lock);
dput(tmp);
goto out_iput;
}
@@ -1502,7 +1506,7 @@ struct dentry *d_obtain_alias(struct inode *inode)
hlist_bl_add_head(&tmp->d_hash, &tmp->d_sb->s_anon);
__bit_spin_unlock(0, (unsigned long *)&tmp->d_sb->s_anon);
spin_unlock(&tmp->d_lock);
- spin_unlock(&dcache_inode_lock);
+ spin_unlock(&inode->i_lock);

return tmp;

@@ -1533,18 +1537,18 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)
struct dentry *new = NULL;

if (inode && S_ISDIR(inode->i_mode)) {
- spin_lock(&dcache_inode_lock);
+ spin_lock(&inode->i_lock);
new = __d_find_alias(inode, 1);
if (new) {
BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED));
- spin_unlock(&dcache_inode_lock);
+ spin_unlock(&inode->i_lock);
security_d_instantiate(new, inode);
d_move(new, dentry);
iput(inode);
} else {
- /* already taking dcache_inode_lock, so d_add() by hand */
+ /* already taking inode->i_lock, so d_add() by hand */
__d_instantiate(dentry, inode);
- spin_unlock(&dcache_inode_lock);
+ spin_unlock(&inode->i_lock);
security_d_instantiate(dentry, inode);
d_rehash(dentry);
}
@@ -1617,10 +1621,10 @@ struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode,
* Negative dentry: instantiate it unless the inode is a directory and
* already has a dentry.
*/
- spin_lock(&dcache_inode_lock);
+ spin_lock(&inode->i_lock);
if (!S_ISDIR(inode->i_mode) || list_empty(&inode->i_dentry)) {
__d_instantiate(found, inode);
- spin_unlock(&dcache_inode_lock);
+ spin_unlock(&inode->i_lock);
security_d_instantiate(found, inode);
return found;
}
@@ -1631,7 +1635,7 @@ struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode,
*/
new = list_entry(inode->i_dentry.next, struct dentry, d_alias);
__dget(new);
- spin_unlock(&dcache_inode_lock);
+ spin_unlock(&inode->i_lock);
security_d_instantiate(found, inode);
d_move(new, found);
iput(inode);
@@ -1951,15 +1955,17 @@ EXPORT_SYMBOL(d_validate);

void d_delete(struct dentry * dentry)
{
+ struct inode *inode;
int isdir = 0;
/*
* Are we the only user?
*/
again:
spin_lock(&dentry->d_lock);
- isdir = S_ISDIR(dentry->d_inode->i_mode);
+ inode = dentry->d_inode;
+ isdir = S_ISDIR(inode->i_mode);
if (dentry->d_count == 1) {
- if (!spin_trylock(&dcache_inode_lock)) {
+ if (inode && !spin_trylock(&inode->i_lock)) {
spin_unlock(&dentry->d_lock);
cpu_relax();
goto again;
@@ -2181,13 +2187,13 @@ struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2)
* This helper attempts to cope with remotely renamed directories
*
* It assumes that the caller is already holding
- * dentry->d_parent->d_inode->i_mutex and the dcache_inode_lock
+ * dentry->d_parent->d_inode->i_mutex and the inode->i_lock
*
* Note: If ever the locking in lock_rename() changes, then please
* remember to update this too...
*/
-static struct dentry *__d_unalias(struct dentry *dentry, struct dentry *alias)
- __releases(dcache_inode_lock)
+static struct dentry *__d_unalias(struct inode *inode,
+ struct dentry *dentry, struct dentry *alias)
{
struct mutex *m1 = NULL, *m2 = NULL;
struct dentry *ret;
@@ -2213,7 +2219,7 @@ out_unalias:
d_move(alias, dentry);
ret = alias;
out_err:
- spin_unlock(&dcache_inode_lock);
+ spin_unlock(&inode->i_lock);
if (m2)
mutex_unlock(m2);
if (m1)
@@ -2291,7 +2297,7 @@ struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
goto out_nolock;
}

- spin_lock(&dcache_inode_lock);
+ spin_lock(&inode->i_lock);

if (S_ISDIR(inode->i_mode)) {
struct dentry *alias;
@@ -2313,7 +2319,7 @@ struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
goto found;
}
/* Nope, but we must(!) avoid directory aliasing */
- actual = __d_unalias(dentry, alias);
+ actual = __d_unalias(inode, dentry, alias);
if (IS_ERR(actual))
dput(alias);
goto out_nolock;
@@ -2331,7 +2337,7 @@ struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
found:
_d_rehash(actual);
spin_unlock(&actual->d_lock);
- spin_unlock(&dcache_inode_lock);
+ spin_unlock(&inode->i_lock);
out_nolock:
if (actual == dentry) {
security_d_instantiate(dentry, inode);
diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c
index f06a940..4b68257 100644
--- a/fs/exportfs/expfs.c
+++ b/fs/exportfs/expfs.c
@@ -43,24 +43,26 @@ find_acceptable_alias(struct dentry *result,
void *context)
{
struct dentry *dentry, *toput = NULL;
+ struct inode *inode;

if (acceptable(context, result))
return result;

- spin_lock(&dcache_inode_lock);
- list_for_each_entry(dentry, &result->d_inode->i_dentry, d_alias) {
+ inode = result->d_inode;
+ spin_lock(&inode->i_lock);
+ list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
dget(dentry);
- spin_unlock(&dcache_inode_lock);
+ spin_unlock(&inode->i_lock);
if (toput)
dput(toput);
if (dentry != result && acceptable(context, dentry)) {
dput(result);
return dentry;
}
- spin_lock(&dcache_inode_lock);
+ spin_lock(&inode->i_lock);
toput = dentry;
}
- spin_unlock(&dcache_inode_lock);
+ spin_unlock(&inode->i_lock);

if (toput)
dput(toput);
diff --git a/fs/nfs/getroot.c b/fs/nfs/getroot.c
index c3a5a11..5596c6a 100644
--- a/fs/nfs/getroot.c
+++ b/fs/nfs/getroot.c
@@ -63,11 +63,11 @@ static int nfs_superblock_set_dummy_root(struct super_block *sb, struct inode *i
* This again causes shrink_dcache_for_umount_subtree() to
* Oops, since the test for IS_ROOT() will fail.
*/
- spin_lock(&dcache_inode_lock);
+ spin_lock(&sb->s_root->d_inode->i_lock);
spin_lock(&sb->s_root->d_lock);
list_del_init(&sb->s_root->d_alias);
spin_unlock(&sb->s_root->d_lock);
- spin_unlock(&dcache_inode_lock);
+ spin_unlock(&sb->s_root->d_inode->i_lock);
}
return 0;
}
diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index 9be6ec1..79b47cb 100644
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -59,7 +59,7 @@ void __fsnotify_update_child_dentry_flags(struct inode *inode)
/* determine if the children should tell inode about their events */
watched = fsnotify_inode_watches_children(inode);

- spin_lock(&dcache_inode_lock);
+ spin_lock(&inode->i_lock);
/* run all of the dentries associated with this inode. Since this is a
* directory, there damn well better only be one item on this list */
list_for_each_entry(alias, &inode->i_dentry, d_alias) {
@@ -82,7 +82,7 @@ void __fsnotify_update_child_dentry_flags(struct inode *inode)
}
spin_unlock(&alias->d_lock);
}
- spin_unlock(&dcache_inode_lock);
+ spin_unlock(&inode->i_lock);
}

/* Notify this dentry's parent about a child's events. */
diff --git a/fs/ocfs2/dcache.c b/fs/ocfs2/dcache.c
index 8b26b54..b4d9421 100644
--- a/fs/ocfs2/dcache.c
+++ b/fs/ocfs2/dcache.c
@@ -169,7 +169,7 @@ struct dentry *ocfs2_find_local_alias(struct inode *inode,
struct list_head *p;
struct dentry *dentry = NULL;

- spin_lock(&dcache_inode_lock);
+ spin_lock(&inode->i_lock);
list_for_each(p, &inode->i_dentry) {
dentry = list_entry(p, struct dentry, d_alias);

@@ -187,7 +187,7 @@ struct dentry *ocfs2_find_local_alias(struct inode *inode,
dentry = NULL;
}

- spin_unlock(&dcache_inode_lock);
+ spin_unlock(&inode->i_lock);

return dentry;
}
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 97c2d78..8ff803b 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -193,7 +193,6 @@ struct dentry_operations {
#define DCACHE_OP_REVALIDATE_EITHER \
(DCACHE_OP_REVALIDATE|DCACHE_OP_REVALIDATE_RCU)

-extern spinlock_t dcache_inode_lock;
extern seqlock_t rename_lock;

/**
--
1.7.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/