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fs: scale inode alias list
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Add a new lock, dcache_inode_lock, to protect the inode's i_dentry list
from concurrent modification. d_alias is also protected by d_lock.

Signed-off-by: Nick Piggin <[email protected]>
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Nick Piggin committed Jan 7, 2011
1 parent 2fd6b7f commit b23fb0a
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Showing 9 changed files with 78 additions and 9 deletions.
2 changes: 2 additions & 0 deletions fs/9p/vfs_inode.c
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Original file line number Diff line number Diff line change
Expand Up @@ -271,9 +271,11 @@ static struct dentry *v9fs_dentry_from_dir_inode(struct inode *inode)
struct dentry *dentry;

spin_lock(&dcache_lock);
spin_lock(&dcache_inode_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(&dcache_lock);
return dentry;
}
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2 changes: 2 additions & 0 deletions fs/affs/amigaffs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -129,6 +129,7 @@ affs_fix_dcache(struct dentry *dentry, u32 entry_ino)
struct list_head *head, *next;

spin_lock(&dcache_lock);
spin_lock(&dcache_inode_lock);
head = &inode->i_dentry;
next = head->next;
while (next != head) {
Expand All @@ -139,6 +140,7 @@ affs_fix_dcache(struct dentry *dentry, u32 entry_ino)
}
next = next->next;
}
spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
}

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3 changes: 3 additions & 0 deletions fs/cifs/inode.c
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Original file line number Diff line number Diff line change
Expand Up @@ -810,12 +810,15 @@ inode_has_hashed_dentries(struct inode *inode)
struct dentry *dentry;

spin_lock(&dcache_lock);
spin_lock(&dcache_inode_lock);
list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
if (!d_unhashed(dentry) || IS_ROOT(dentry)) {
spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
return true;
}
}
spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
return false;
}
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66 changes: 58 additions & 8 deletions fs/dcache.c
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Original file line number Diff line number Diff line change
Expand Up @@ -37,6 +37,8 @@

/*
* Usage:
* dcache_inode_lock protects:
* - i_dentry, d_alias, d_inode
* dcache_hash_lock protects:
* - the dcache hash table, s_anon lists
* dcache_lru_lock protects:
Expand All @@ -49,12 +51,14 @@
* - d_unhashed()
* - d_parent and d_subdirs
* - childrens' d_child and d_parent
* - d_alias, d_inode
*
* Ordering:
* dcache_lock
* dentry->d_lock
* dcache_lru_lock
* dcache_hash_lock
* dcache_inode_lock
* dentry->d_lock
* dcache_lru_lock
* dcache_hash_lock
*
* If there is an ancestor relationship:
* dentry->d_parent->...->d_parent->d_lock
Expand All @@ -70,11 +74,13 @@
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_hash_lock);
static __cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lru_lock);
__cacheline_aligned_in_smp DEFINE_SPINLOCK(dcache_lock);
__cacheline_aligned_in_smp DEFINE_SEQLOCK(rename_lock);

EXPORT_SYMBOL(dcache_inode_lock);
EXPORT_SYMBOL(dcache_lock);

static struct kmem_cache *dentry_cache __read_mostly;
Expand Down Expand Up @@ -154,13 +160,15 @@ static void d_free(struct dentry *dentry)
*/
static void dentry_iput(struct dentry * dentry)
__releases(dentry->d_lock)
__releases(dcache_inode_lock)
__releases(dcache_lock)
{
struct inode *inode = dentry->d_inode;
if (inode) {
dentry->d_inode = NULL;
list_del_init(&dentry->d_alias);
spin_unlock(&dentry->d_lock);
spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
if (!inode->i_nlink)
fsnotify_inoderemove(inode);
Expand All @@ -170,6 +178,7 @@ static void dentry_iput(struct dentry * dentry)
iput(inode);
} else {
spin_unlock(&dentry->d_lock);
spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
}
}
Expand Down Expand Up @@ -231,6 +240,7 @@ 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(dcache_lock)
{
list_del(&dentry->d_u.d_child);
Expand Down Expand Up @@ -332,13 +342,18 @@ void dput(struct dentry *dentry)
* want to reduce dcache_lock anyway so this will
* get improved.
*/
drop1:
spin_unlock(&dentry->d_lock);
goto repeat;
}
if (parent && !spin_trylock(&parent->d_lock)) {
spin_unlock(&dentry->d_lock);
if (!spin_trylock(&dcache_inode_lock)) {
drop2:
spin_unlock(&dcache_lock);
goto repeat;
goto drop1;
}
if (parent && !spin_trylock(&parent->d_lock)) {
spin_unlock(&dcache_inode_lock);
goto drop2;
}
}
dentry->d_count--;
Expand Down Expand Up @@ -369,6 +384,7 @@ void dput(struct dentry *dentry)
spin_unlock(&dentry->d_lock);
if (parent)
spin_unlock(&parent->d_lock);
spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
return;

Expand Down Expand Up @@ -558,7 +574,9 @@ struct dentry *d_find_alias(struct inode *inode)

if (!list_empty(&inode->i_dentry)) {
spin_lock(&dcache_lock);
spin_lock(&dcache_inode_lock);
de = __d_find_alias(inode, 0);
spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
}
return de;
Expand All @@ -574,18 +592,21 @@ void d_prune_aliases(struct inode *inode)
struct dentry *dentry;
restart:
spin_lock(&dcache_lock);
spin_lock(&dcache_inode_lock);
list_for_each_entry(dentry, &inode->i_dentry, d_alias) {
spin_lock(&dentry->d_lock);
if (!dentry->d_count) {
__dget_locked_dlock(dentry);
__d_drop(dentry);
spin_unlock(&dentry->d_lock);
spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
dput(dentry);
goto restart;
}
spin_unlock(&dentry->d_lock);
}
spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
}
EXPORT_SYMBOL(d_prune_aliases);
Expand All @@ -601,6 +622,7 @@ EXPORT_SYMBOL(d_prune_aliases);
static void prune_one_dentry(struct dentry *dentry, struct dentry *parent)
__releases(dentry->d_lock)
__releases(parent->d_lock)
__releases(dcache_inode_lock)
__releases(dcache_lock)
{
__d_drop(dentry);
Expand All @@ -612,6 +634,7 @@ static void prune_one_dentry(struct dentry *dentry, struct dentry *parent)
*/
while (dentry) {
spin_lock(&dcache_lock);
spin_lock(&dcache_inode_lock);
again:
spin_lock(&dentry->d_lock);
if (IS_ROOT(dentry))
Expand All @@ -627,6 +650,7 @@ static void prune_one_dentry(struct dentry *dentry, struct dentry *parent)
if (parent)
spin_unlock(&parent->d_lock);
spin_unlock(&dentry->d_lock);
spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
return;
}
Expand Down Expand Up @@ -676,8 +700,9 @@ static void shrink_dentry_list(struct list_head *list)
spin_unlock(&dcache_lru_lock);

prune_one_dentry(dentry, parent);
/* dcache_lock and dentry->d_lock dropped */
/* dcache_lock, dcache_inode_lock and dentry->d_lock dropped */
spin_lock(&dcache_lock);
spin_lock(&dcache_inode_lock);
spin_lock(&dcache_lru_lock);
}
}
Expand All @@ -699,6 +724,7 @@ static void __shrink_dcache_sb(struct super_block *sb, int *count, int flags)
int cnt = *count;

spin_lock(&dcache_lock);
spin_lock(&dcache_inode_lock);
relock:
spin_lock(&dcache_lru_lock);
while (!list_empty(&sb->s_dentry_lru)) {
Expand Down Expand Up @@ -737,8 +763,8 @@ static void __shrink_dcache_sb(struct super_block *sb, int *count, int flags)
if (!list_empty(&referenced))
list_splice(&referenced, &sb->s_dentry_lru);
spin_unlock(&dcache_lru_lock);
spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);

}

/**
Expand Down Expand Up @@ -832,12 +858,14 @@ void shrink_dcache_sb(struct super_block *sb)
LIST_HEAD(tmp);

spin_lock(&dcache_lock);
spin_lock(&dcache_inode_lock);
spin_lock(&dcache_lru_lock);
while (!list_empty(&sb->s_dentry_lru)) {
list_splice_init(&sb->s_dentry_lru, &tmp);
shrink_dentry_list(&tmp);
}
spin_unlock(&dcache_lru_lock);
spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
}
EXPORT_SYMBOL(shrink_dcache_sb);
Expand Down Expand Up @@ -1255,9 +1283,11 @@ EXPORT_SYMBOL(d_alloc_name);
/* the caller must hold dcache_lock */
static void __d_instantiate(struct dentry *dentry, struct inode *inode)
{
spin_lock(&dentry->d_lock);
if (inode)
list_add(&dentry->d_alias, &inode->i_dentry);
dentry->d_inode = inode;
spin_unlock(&dentry->d_lock);
fsnotify_d_instantiate(dentry, inode);
}

Expand All @@ -1280,7 +1310,9 @@ void d_instantiate(struct dentry *entry, struct inode * inode)
{
BUG_ON(!list_empty(&entry->d_alias));
spin_lock(&dcache_lock);
spin_lock(&dcache_inode_lock);
__d_instantiate(entry, inode);
spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
security_d_instantiate(entry, inode);
}
Expand Down Expand Up @@ -1341,7 +1373,9 @@ struct dentry *d_instantiate_unique(struct dentry *entry, struct inode *inode)
BUG_ON(!list_empty(&entry->d_alias));

spin_lock(&dcache_lock);
spin_lock(&dcache_inode_lock);
result = __d_instantiate_unique(entry, inode);
spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);

if (!result) {
Expand Down Expand Up @@ -1432,8 +1466,10 @@ struct dentry *d_obtain_alias(struct inode *inode)
tmp->d_parent = tmp; /* make sure dput doesn't croak */

spin_lock(&dcache_lock);
spin_lock(&dcache_inode_lock);
res = __d_find_alias(inode, 0);
if (res) {
spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
dput(tmp);
goto out_iput;
Expand All @@ -1450,6 +1486,7 @@ struct dentry *d_obtain_alias(struct inode *inode)
hlist_add_head(&tmp->d_hash, &inode->i_sb->s_anon);
spin_unlock(&dcache_hash_lock);
spin_unlock(&tmp->d_lock);
spin_unlock(&dcache_inode_lock);

spin_unlock(&dcache_lock);
return tmp;
Expand Down Expand Up @@ -1482,16 +1519,19 @@ struct dentry *d_splice_alias(struct inode *inode, struct dentry *dentry)

if (inode && S_ISDIR(inode->i_mode)) {
spin_lock(&dcache_lock);
spin_lock(&dcache_inode_lock);
new = __d_find_alias(inode, 1);
if (new) {
BUG_ON(!(new->d_flags & DCACHE_DISCONNECTED));
spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
security_d_instantiate(new, inode);
d_move(new, dentry);
iput(inode);
} else {
/* already taking dcache_lock, so d_add() by hand */
__d_instantiate(dentry, inode);
spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
security_d_instantiate(dentry, inode);
d_rehash(dentry);
Expand Down Expand Up @@ -1566,8 +1606,10 @@ struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode,
* already has a dentry.
*/
spin_lock(&dcache_lock);
spin_lock(&dcache_inode_lock);
if (!S_ISDIR(inode->i_mode) || list_empty(&inode->i_dentry)) {
__d_instantiate(found, inode);
spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
security_d_instantiate(found, inode);
return found;
Expand All @@ -1579,6 +1621,7 @@ struct dentry *d_add_ci(struct dentry *dentry, struct inode *inode,
*/
new = list_entry(inode->i_dentry.next, struct dentry, d_alias);
dget_locked(new);
spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
security_d_instantiate(found, inode);
d_move(new, found);
Expand Down Expand Up @@ -1797,6 +1840,7 @@ void d_delete(struct dentry * dentry)
* Are we the only user?
*/
spin_lock(&dcache_lock);
spin_lock(&dcache_inode_lock);
spin_lock(&dentry->d_lock);
isdir = S_ISDIR(dentry->d_inode->i_mode);
if (dentry->d_count == 1) {
Expand All @@ -1810,6 +1854,7 @@ void d_delete(struct dentry * dentry)
__d_drop(dentry);

spin_unlock(&dentry->d_lock);
spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);

fsnotify_nameremove(dentry, isdir);
Expand Down Expand Up @@ -2067,6 +2112,7 @@ struct dentry *d_ancestor(struct dentry *p1, struct dentry *p2)
*/
static struct dentry *__d_unalias(struct dentry *dentry, struct dentry *alias)
__releases(dcache_lock)
__releases(dcache_inode_lock)
{
struct mutex *m1 = NULL, *m2 = NULL;
struct dentry *ret;
Expand All @@ -2092,6 +2138,7 @@ static struct dentry *__d_unalias(struct dentry *dentry, struct dentry *alias)
d_move_locked(alias, dentry);
ret = alias;
out_err:
spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
if (m2)
mutex_unlock(m2);
Expand Down Expand Up @@ -2153,6 +2200,7 @@ struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
BUG_ON(!d_unhashed(dentry));

spin_lock(&dcache_lock);
spin_lock(&dcache_inode_lock);

if (!inode) {
actual = dentry;
Expand Down Expand Up @@ -2196,6 +2244,7 @@ struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
_d_rehash(actual);
spin_unlock(&dcache_hash_lock);
spin_unlock(&actual->d_lock);
spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
out_nolock:
if (actual == dentry) {
Expand All @@ -2207,6 +2256,7 @@ struct dentry *d_materialise_unique(struct dentry *dentry, struct inode *inode)
return actual;

shouldnt_be_hashed:
spin_unlock(&dcache_inode_lock);
spin_unlock(&dcache_lock);
BUG();
}
Expand Down
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