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-rw-r--r--fs/dquot.c218
-rw-r--r--include/linux/quotaops.h2
2 files changed, 122 insertions, 98 deletions
diff --git a/fs/dquot.c b/fs/dquot.c
index 48c0571f831d..bca3cac4bee7 100644
--- a/fs/dquot.c
+++ b/fs/dquot.c
@@ -87,14 +87,17 @@
#define __DQUOT_PARANOIA
/*
- * There are two quota SMP locks. dq_list_lock protects all lists with quotas
- * and quota formats and also dqstats structure containing statistics about the
- * lists. dq_data_lock protects data from dq_dqb and also mem_dqinfo structures
- * and also guards consistency of dquot->dq_dqb with inode->i_blocks, i_bytes.
+ * There are three quota SMP locks. dq_list_lock protects all lists with quotas
+ * and quota formats, dqstats structure containing statistics about the lists
+ * dq_data_lock protects data from dq_dqb and also mem_dqinfo structures and
+ * also guards consistency of dquot->dq_dqb with inode->i_blocks, i_bytes.
* i_blocks and i_bytes updates itself are guarded by i_lock acquired directly
- * in inode_add_bytes() and inode_sub_bytes().
+ * in inode_add_bytes() and inode_sub_bytes(). dq_state_lock protects
+ * modifications of quota state (on quotaon and quotaoff) and readers who care
+ * about latest values take it as well.
*
- * The spinlock ordering is hence: dq_data_lock > dq_list_lock > i_lock
+ * The spinlock ordering is hence: dq_data_lock > dq_list_lock > i_lock,
+ * dq_list_lock > dq_state_lock
*
* Note that some things (eg. sb pointer, type, id) doesn't change during
* the life of the dquot structure and so needn't to be protected by a lock
@@ -103,12 +106,7 @@
* operation is just reading pointers from inode (or not using them at all) the
* read lock is enough. If pointers are altered function must hold write lock
* (these locking rules also apply for S_NOQUOTA flag in the inode - note that
- * for altering the flag i_mutex is also needed). If operation is holding
- * reference to dquot in other way (e.g. quotactl ops) it must be guarded by
- * dqonoff_mutex.
- * This locking assures that:
- * a) update/access to dquot pointers in inode is serialized
- * b) everyone is guarded against invalidate_dquots()
+ * for altering the flag i_mutex is also needed).
*
* Each dquot has its dq_lock mutex. Locked dquots might not be referenced
* from inodes (dquot_alloc_space() and such don't check the dq_lock).
@@ -122,10 +120,17 @@
* Lock ordering (including related VFS locks) is the following:
* i_mutex > dqonoff_sem > journal_lock > dqptr_sem > dquot->dq_lock >
* dqio_mutex
+ * The lock ordering of dqptr_sem imposed by quota code is only dqonoff_sem >
+ * dqptr_sem. But filesystem has to count with the fact that functions such as
+ * dquot_alloc_space() acquire dqptr_sem and they usually have to be called
+ * from inside a transaction to keep filesystem consistency after a crash. Also
+ * filesystems usually want to do some IO on dquot from ->mark_dirty which is
+ * called with dqptr_sem held.
* i_mutex on quota files is special (it's below dqio_mutex)
*/
static DEFINE_SPINLOCK(dq_list_lock);
+static DEFINE_SPINLOCK(dq_state_lock);
DEFINE_SPINLOCK(dq_data_lock);
static char *quotatypes[] = INITQFNAMES;
@@ -428,7 +433,7 @@ static inline void do_destroy_dquot(struct dquot *dquot)
* quota is disabled and pointers from inodes removed so there cannot be new
* quota users. There can still be some users of quotas due to inodes being
* just deleted or pruned by prune_icache() (those are not attached to any
- * list). We have to wait for such users.
+ * list) or parallel quotactl call. We have to wait for such users.
*/
static void invalidate_dquots(struct super_block *sb, int type)
{
@@ -600,7 +605,6 @@ static struct shrinker dqcache_shrinker = {
/*
* Put reference to dquot
* NOTE: If you change this function please check whether dqput_blocks() works right...
- * MUST be called with either dqptr_sem or dqonoff_mutex held
*/
void dqput(struct dquot *dquot)
{
@@ -697,36 +701,30 @@ static struct dquot *get_empty_dquot(struct super_block *sb, int type)
}
/*
- * Check whether dquot is in memory.
- * MUST be called with either dqptr_sem or dqonoff_mutex held
- */
-int dquot_is_cached(struct super_block *sb, unsigned int id, int type)
-{
- unsigned int hashent = hashfn(sb, id, type);
- int ret = 0;
-
- if (!sb_has_quota_active(sb, type))
- return 0;
- spin_lock(&dq_list_lock);
- if (find_dquot(hashent, sb, id, type) != NODQUOT)
- ret = 1;
- spin_unlock(&dq_list_lock);
- return ret;
-}
-
-/*
* Get reference to dquot
- * MUST be called with either dqptr_sem or dqonoff_mutex held
+ *
+ * Locking is slightly tricky here. We are guarded from parallel quotaoff()
+ * destroying our dquot by:
+ * a) checking for quota flags under dq_list_lock and
+ * b) getting a reference to dquot before we release dq_list_lock
*/
struct dquot *dqget(struct super_block *sb, unsigned int id, int type)
{
unsigned int hashent = hashfn(sb, id, type);
- struct dquot *dquot, *empty = NODQUOT;
+ struct dquot *dquot = NODQUOT, *empty = NODQUOT;
if (!sb_has_quota_active(sb, type))
return NODQUOT;
we_slept:
spin_lock(&dq_list_lock);
+ spin_lock(&dq_state_lock);
+ if (!sb_has_quota_active(sb, type)) {
+ spin_unlock(&dq_state_lock);
+ spin_unlock(&dq_list_lock);
+ goto out;
+ }
+ spin_unlock(&dq_state_lock);
+
if ((dquot = find_dquot(hashent, sb, id, type)) == NODQUOT) {
if (empty == NODQUOT) {
spin_unlock(&dq_list_lock);
@@ -735,6 +733,7 @@ we_slept:
goto we_slept;
}
dquot = empty;
+ empty = NODQUOT;
dquot->dq_id = id;
/* all dquots go on the inuse_list */
put_inuse(dquot);
@@ -749,8 +748,6 @@ we_slept:
dqstats.cache_hits++;
dqstats.lookups++;
spin_unlock(&dq_list_lock);
- if (empty)
- do_destroy_dquot(empty);
}
/* Wait for dq_lock - after this we know that either dquot_release() is already
* finished or it will be canceled due to dq_count > 1 test */
@@ -758,11 +755,15 @@ we_slept:
/* Read the dquot and instantiate it (everything done only if needed) */
if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags) && sb->dq_op->acquire_dquot(dquot) < 0) {
dqput(dquot);
- return NODQUOT;
+ dquot = NODQUOT;
+ goto out;
}
#ifdef __DQUOT_PARANOIA
BUG_ON(!dquot->dq_sb); /* Has somebody invalidated entry under us? */
#endif
+out:
+ if (empty)
+ do_destroy_dquot(empty);
return dquot;
}
@@ -1198,63 +1199,76 @@ static int info_bdq_free(struct dquot *dquot, qsize_t space)
}
/*
* Initialize quota pointers in inode
- * Transaction must be started at entry
+ * We do things in a bit complicated way but by that we avoid calling
+ * dqget() and thus filesystem callbacks under dqptr_sem.
*/
int dquot_initialize(struct inode *inode, int type)
{
unsigned int id = 0;
int cnt, ret = 0;
+ struct dquot *got[MAXQUOTAS] = { NODQUOT, NODQUOT };
+ struct super_block *sb = inode->i_sb;
/* First test before acquiring mutex - solves deadlocks when we
* re-enter the quota code and are already holding the mutex */
if (IS_NOQUOTA(inode))
return 0;
- down_write(&sb_dqopt(inode->i_sb)->dqptr_sem);
+
+ /* First get references to structures we might need. */
+ for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
+ if (type != -1 && cnt != type)
+ continue;
+ switch (cnt) {
+ case USRQUOTA:
+ id = inode->i_uid;
+ break;
+ case GRPQUOTA:
+ id = inode->i_gid;
+ break;
+ }
+ got[cnt] = dqget(sb, id, cnt);
+ }
+
+ down_write(&sb_dqopt(sb)->dqptr_sem);
/* Having dqptr_sem we know NOQUOTA flags can't be altered... */
if (IS_NOQUOTA(inode))
goto out_err;
for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
if (type != -1 && cnt != type)
continue;
+ /* Avoid races with quotaoff() */
+ if (!sb_has_quota_active(sb, cnt))
+ continue;
if (inode->i_dquot[cnt] == NODQUOT) {
- switch (cnt) {
- case USRQUOTA:
- id = inode->i_uid;
- break;
- case GRPQUOTA:
- id = inode->i_gid;
- break;
- }
- inode->i_dquot[cnt] = dqget(inode->i_sb, id, cnt);
+ inode->i_dquot[cnt] = got[cnt];
+ got[cnt] = NODQUOT;
}
}
out_err:
- up_write(&sb_dqopt(inode->i_sb)->dqptr_sem);
+ up_write(&sb_dqopt(sb)->dqptr_sem);
+ /* Drop unused references */
+ for (cnt = 0; cnt < MAXQUOTAS; cnt++)
+ dqput(got[cnt]);
return ret;
}
/*
* Release all quotas referenced by inode
- * Transaction must be started at an entry
*/
-int dquot_drop_locked(struct inode *inode)
+int dquot_drop(struct inode *inode)
{
int cnt;
+ struct dquot *put[MAXQUOTAS];
+ down_write(&sb_dqopt(inode->i_sb)->dqptr_sem);
for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
- if (inode->i_dquot[cnt] != NODQUOT) {
- dqput(inode->i_dquot[cnt]);
- inode->i_dquot[cnt] = NODQUOT;
- }
+ put[cnt] = inode->i_dquot[cnt];
+ inode->i_dquot[cnt] = NODQUOT;
}
- return 0;
-}
-
-int dquot_drop(struct inode *inode)
-{
- down_write(&sb_dqopt(inode->i_sb)->dqptr_sem);
- dquot_drop_locked(inode);
up_write(&sb_dqopt(inode->i_sb)->dqptr_sem);
+
+ for (cnt = 0; cnt < MAXQUOTAS; cnt++)
+ dqput(put[cnt]);
return 0;
}
@@ -1470,8 +1484,9 @@ int dquot_transfer(struct inode *inode, struct iattr *iattr)
qsize_t space;
struct dquot *transfer_from[MAXQUOTAS];
struct dquot *transfer_to[MAXQUOTAS];
- int cnt, ret = NO_QUOTA, chuid = (iattr->ia_valid & ATTR_UID) && inode->i_uid != iattr->ia_uid,
- chgid = (iattr->ia_valid & ATTR_GID) && inode->i_gid != iattr->ia_gid;
+ int cnt, ret = QUOTA_OK;
+ int chuid = iattr->ia_valid & ATTR_UID && inode->i_uid != iattr->ia_uid,
+ chgid = iattr->ia_valid & ATTR_GID && inode->i_gid != iattr->ia_gid;
char warntype_to[MAXQUOTAS];
char warntype_from_inodes[MAXQUOTAS], warntype_from_space[MAXQUOTAS];
@@ -1479,21 +1494,11 @@ int dquot_transfer(struct inode *inode, struct iattr *iattr)
* re-enter the quota code and are already holding the mutex */
if (IS_NOQUOTA(inode))
return QUOTA_OK;
- /* Clear the arrays */
+ /* Initialize the arrays */
for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
- transfer_to[cnt] = transfer_from[cnt] = NODQUOT;
+ transfer_from[cnt] = NODQUOT;
+ transfer_to[cnt] = NODQUOT;
warntype_to[cnt] = QUOTA_NL_NOWARN;
- }
- down_write(&sb_dqopt(inode->i_sb)->dqptr_sem);
- /* Now recheck reliably when holding dqptr_sem */
- if (IS_NOQUOTA(inode)) { /* File without quota accounting? */
- up_write(&sb_dqopt(inode->i_sb)->dqptr_sem);
- return QUOTA_OK;
- }
- /* First build the transfer_to list - here we can block on
- * reading/instantiating of dquots. We know that the transaction for
- * us was already started so we don't violate lock ranking here */
- for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
switch (cnt) {
case USRQUOTA:
if (!chuid)
@@ -1507,6 +1512,13 @@ int dquot_transfer(struct inode *inode, struct iattr *iattr)
break;
}
}
+
+ down_write(&sb_dqopt(inode->i_sb)->dqptr_sem);
+ /* Now recheck reliably when holding dqptr_sem */
+ if (IS_NOQUOTA(inode)) { /* File without quota accounting? */
+ up_write(&sb_dqopt(inode->i_sb)->dqptr_sem);
+ goto put_all;
+ }
spin_lock(&dq_data_lock);
space = inode_get_bytes(inode);
/* Build the transfer_from list and check the limits */
@@ -1517,7 +1529,7 @@ int dquot_transfer(struct inode *inode, struct iattr *iattr)
if (check_idq(transfer_to[cnt], 1, warntype_to + cnt) ==
NO_QUOTA || check_bdq(transfer_to[cnt], space, 0,
warntype_to + cnt) == NO_QUOTA)
- goto warn_put_all;
+ goto over_quota;
}
/*
@@ -1545,28 +1557,37 @@ int dquot_transfer(struct inode *inode, struct iattr *iattr)
inode->i_dquot[cnt] = transfer_to[cnt];
}
- ret = QUOTA_OK;
-warn_put_all:
spin_unlock(&dq_data_lock);
+ up_write(&sb_dqopt(inode->i_sb)->dqptr_sem);
+
/* Dirtify all the dquots - this can block when journalling */
for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
if (transfer_from[cnt])
mark_dquot_dirty(transfer_from[cnt]);
- if (transfer_to[cnt])
+ if (transfer_to[cnt]) {
mark_dquot_dirty(transfer_to[cnt]);
+ /* The reference we got is transferred to the inode */
+ transfer_to[cnt] = NODQUOT;
+ }
}
+warn_put_all:
flush_warnings(transfer_to, warntype_to);
flush_warnings(transfer_from, warntype_from_inodes);
flush_warnings(transfer_from, warntype_from_space);
-
+put_all:
for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
- if (ret == QUOTA_OK && transfer_from[cnt] != NODQUOT)
- dqput(transfer_from[cnt]);
- if (ret == NO_QUOTA && transfer_to[cnt] != NODQUOT)
- dqput(transfer_to[cnt]);
+ dqput(transfer_from[cnt]);
+ dqput(transfer_to[cnt]);
}
- up_write(&sb_dqopt(inode->i_sb)->dqptr_sem);
return ret;
+over_quota:
+ spin_unlock(&dq_data_lock);
+ up_write(&sb_dqopt(inode->i_sb)->dqptr_sem);
+ /* Clear dquot pointers we don't want to dqput() */
+ for (cnt = 0; cnt < MAXQUOTAS; cnt++)
+ transfer_from[cnt] = NODQUOT;
+ ret = NO_QUOTA;
+ goto warn_put_all;
}
/* Wrapper for transferring ownership of an inode */
@@ -1651,19 +1672,24 @@ int vfs_quota_disable(struct super_block *sb, int type, unsigned int flags)
continue;
if (flags & DQUOT_SUSPENDED) {
+ spin_lock(&dq_state_lock);
dqopt->flags |=
dquot_state_flag(DQUOT_SUSPENDED, cnt);
+ spin_unlock(&dq_state_lock);
} else {
+ spin_lock(&dq_state_lock);
dqopt->flags &= ~dquot_state_flag(flags, cnt);
/* Turning off suspended quotas? */
if (!sb_has_quota_loaded(sb, cnt) &&
sb_has_quota_suspended(sb, cnt)) {
dqopt->flags &= ~dquot_state_flag(
DQUOT_SUSPENDED, cnt);
+ spin_unlock(&dq_state_lock);
iput(dqopt->files[cnt]);
dqopt->files[cnt] = NULL;
continue;
}
+ spin_unlock(&dq_state_lock);
}
/* We still have to keep quota loaded? */
@@ -1830,7 +1856,9 @@ static int vfs_load_quota_inode(struct inode *inode, int type, int format_id,
}
mutex_unlock(&dqopt->dqio_mutex);
mutex_unlock(&inode->i_mutex);
+ spin_lock(&dq_state_lock);
dqopt->flags |= dquot_state_flag(flags, type);
+ spin_unlock(&dq_state_lock);
add_dquot_ref(sb, type);
mutex_unlock(&dqopt->dqonoff_mutex);
@@ -1872,9 +1900,11 @@ static int vfs_quota_on_remount(struct super_block *sb, int type)
}
inode = dqopt->files[type];
dqopt->files[type] = NULL;
+ spin_lock(&dq_state_lock);
flags = dqopt->flags & dquot_state_flag(DQUOT_USAGE_ENABLED |
DQUOT_LIMITS_ENABLED, type);
dqopt->flags &= ~dquot_state_flag(DQUOT_STATE_FLAGS, type);
+ spin_unlock(&dq_state_lock);
mutex_unlock(&dqopt->dqonoff_mutex);
flags = dquot_generic_flag(flags, type);
@@ -1952,7 +1982,9 @@ int vfs_quota_enable(struct inode *inode, int type, int format_id,
ret = -EBUSY;
goto out_lock;
}
+ spin_lock(&dq_state_lock);
sb_dqopt(sb)->flags |= dquot_state_flag(flags, type);
+ spin_unlock(&dq_state_lock);
out_lock:
mutex_unlock(&dqopt->dqonoff_mutex);
return ret;
@@ -2039,14 +2071,12 @@ int vfs_get_dqblk(struct super_block *sb, int type, qid_t id, struct if_dqblk *d
{
struct dquot *dquot;
- mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);
- if (!(dquot = dqget(sb, id, type))) {
- mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
+ dquot = dqget(sb, id, type);
+ if (dquot == NODQUOT)
return -ESRCH;
- }
do_get_dqblk(dquot, di);
dqput(dquot);
- mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
+
return 0;
}
@@ -2130,7 +2160,6 @@ int vfs_set_dqblk(struct super_block *sb, int type, qid_t id, struct if_dqblk *d
struct dquot *dquot;
int rc;
- mutex_lock(&sb_dqopt(sb)->dqonoff_mutex);
dquot = dqget(sb, id, type);
if (!dquot) {
rc = -ESRCH;
@@ -2139,7 +2168,6 @@ int vfs_set_dqblk(struct super_block *sb, int type, qid_t id, struct if_dqblk *d
rc = do_set_dqblk(dquot, di);
dqput(dquot);
out:
- mutex_unlock(&sb_dqopt(sb)->dqonoff_mutex);
return rc;
}
@@ -2370,11 +2398,9 @@ EXPORT_SYMBOL(dquot_release);
EXPORT_SYMBOL(dquot_mark_dquot_dirty);
EXPORT_SYMBOL(dquot_initialize);
EXPORT_SYMBOL(dquot_drop);
-EXPORT_SYMBOL(dquot_drop_locked);
EXPORT_SYMBOL(vfs_dq_drop);
EXPORT_SYMBOL(dqget);
EXPORT_SYMBOL(dqput);
-EXPORT_SYMBOL(dquot_is_cached);
EXPORT_SYMBOL(dquot_alloc_space);
EXPORT_SYMBOL(dquot_alloc_inode);
EXPORT_SYMBOL(dquot_free_space);
diff --git a/include/linux/quotaops.h b/include/linux/quotaops.h
index 21b781a3350f..0b35b3a1be05 100644
--- a/include/linux/quotaops.h
+++ b/include/linux/quotaops.h
@@ -24,10 +24,8 @@ void sync_dquots(struct super_block *sb, int type);
int dquot_initialize(struct inode *inode, int type);
int dquot_drop(struct inode *inode);
-int dquot_drop_locked(struct inode *inode);
struct dquot *dqget(struct super_block *sb, unsigned int id, int type);
void dqput(struct dquot *dquot);
-int dquot_is_cached(struct super_block *sb, unsigned int id, int type);
int dquot_scan_active(struct super_block *sb,
int (*fn)(struct dquot *dquot, unsigned long priv),
unsigned long priv);
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-22 18:08:39 +0100