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fs: dcache per-inode inode alias locking
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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 <[email protected]>
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Nick Piggin committed Jan 7, 2011
1 parent ceb5bdc commit 873feea
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Showing 9 changed files with 67 additions and 60 deletions.
4 changes: 2 additions & 2 deletions fs/9p/vfs_inode.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
}

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4 changes: 2 additions & 2 deletions fs/affs/amigaffs.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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) {
Expand All @@ -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);
}


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6 changes: 3 additions & 3 deletions fs/cifs/inode.c
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Original file line number Diff line number Diff line change
Expand Up @@ -809,14 +809,14 @@ inode_has_hashed_dentries(struct inode *inode)
{
struct dentry *dentry;

spin_lock(&dcache_inode_lock);
spin_lock(&inode->i_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(&inode->i_lock);
return true;
}
}
spin_unlock(&dcache_inode_lock);
spin_unlock(&inode->i_lock);
return false;
}

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88 changes: 47 additions & 41 deletions fs/dcache.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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
* s_anon bl list spinlock protects:
Expand All @@ -58,7 +58,7 @@
* - d_alias, d_inode
*
* Ordering:
* dcache_inode_lock
* dentry->d_inode->i_lock
* dentry->d_lock
* dcache_lru_lock
* dcache_hash_bucket lock
Expand All @@ -78,12 +78,10 @@
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;

Expand Down Expand Up @@ -196,14 +194,14 @@ static inline void dentry_rcuwalk_barrier(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) {
dentry->d_inode = NULL;
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)
Expand All @@ -212,7 +210,6 @@ static void dentry_iput(struct dentry * dentry)
iput(inode);
} else {
spin_unlock(&dentry->d_lock);
spin_unlock(&dcache_inode_lock);
}
}

Expand All @@ -222,14 +219,14 @@ static void dentry_iput(struct dentry * dentry)
*/
static void dentry_unlink_inode(struct dentry * dentry)
__releases(dentry->d_lock)
__releases(dcache_inode_lock)
__releases(dentry->d_inode->i_lock)
{
struct inode *inode = dentry->d_inode;
dentry->d_inode = NULL;
list_del_init(&dentry->d_alias);
dentry_rcuwalk_barrier(dentry);
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)
Expand Down Expand Up @@ -295,7 +292,7 @@ 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);
Expand Down Expand Up @@ -370,9 +367,11 @@ EXPORT_SYMBOL(d_drop);
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();
Expand All @@ -383,7 +382,8 @@ static inline struct dentry *dentry_kill(struct dentry *dentry, int ref)
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;
}

Expand Down Expand Up @@ -618,9 +618,9 @@ 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;
}
Expand All @@ -634,20 +634,20 @@ 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);

Expand Down Expand Up @@ -1392,9 +1392,11 @@ 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);
Expand Down Expand Up @@ -1458,9 +1460,11 @@ 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);
Expand Down Expand Up @@ -1542,10 +1546,10 @@ 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;
}
Expand All @@ -1561,7 +1565,7 @@ 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.first);
spin_unlock(&tmp->d_lock);
spin_unlock(&dcache_inode_lock);
spin_unlock(&inode->i_lock);

return tmp;

Expand Down Expand Up @@ -1592,18 +1596,18 @@ 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 got 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);
}
Expand Down Expand Up @@ -1676,10 +1680,10 @@ 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;
}
Expand All @@ -1690,7 +1694,7 @@ 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);
Expand Down Expand Up @@ -2004,15 +2008,17 @@ 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;
Expand Down Expand Up @@ -2266,13 +2272,13 @@ 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;
Expand All @@ -2298,7 +2304,7 @@ static struct dentry *__d_unalias(struct dentry *dentry, struct dentry *alias)
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)
Expand Down Expand Up @@ -2371,7 +2377,7 @@ 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;
Expand All @@ -2388,7 +2394,7 @@ 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;
Expand All @@ -2406,7 +2412,7 @@ 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);
Expand Down
12 changes: 7 additions & 5 deletions fs/exportfs/expfs.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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);
Expand Down
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