diff options
| -rw-r--r-- | fs/quota/dquot.c | 47 |
1 files changed, 11 insertions, 36 deletions
diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c index 3fc62b097be..f6eaf0d8fd6 100644 --- a/fs/quota/dquot.c +++ b/fs/quota/dquot.c @@ -100,9 +100,13 @@ * * Any operation working on dquots via inode pointers must hold dqptr_sem. If * 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). + * read lock is enough. If pointers are altered function must hold write lock. + * Special care needs to be taken about S_NOQUOTA inode flag (marking that + * inode is a quota file). Functions adding pointers from inode to dquots have + * to check this flag under dqptr_sem and then (if S_NOQUOTA is not set) they + * have to do all pointer modifications before dropping dqptr_sem. This makes + * sure they cannot race with quotaon which first sets S_NOQUOTA flag and + * then drops all pointers to dquots from an inode. * * 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). @@ -1275,7 +1279,6 @@ int dquot_initialize(struct inode *inode, int type) } 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++) { @@ -1431,11 +1434,6 @@ int __dquot_alloc_space(struct inode *inode, qsize_t number, } down_read(&sb_dqopt(inode->i_sb)->dqptr_sem); - if (IS_NOQUOTA(inode)) { - inode_incr_space(inode, number, reserve); - goto out_unlock; - } - for (cnt = 0; cnt < MAXQUOTAS; cnt++) warntype[cnt] = QUOTA_NL_NOWARN; @@ -1466,7 +1464,6 @@ int __dquot_alloc_space(struct inode *inode, qsize_t number, mark_all_dquot_dirty(inode->i_dquot); out_flush_warn: flush_warnings(inode->i_dquot, warntype); -out_unlock: up_read(&sb_dqopt(inode->i_sb)->dqptr_sem); out: return ret; @@ -1499,10 +1496,6 @@ int dquot_alloc_inode(const struct inode *inode, qsize_t number) for (cnt = 0; cnt < MAXQUOTAS; cnt++) warntype[cnt] = QUOTA_NL_NOWARN; down_read(&sb_dqopt(inode->i_sb)->dqptr_sem); - if (IS_NOQUOTA(inode)) { - up_read(&sb_dqopt(inode->i_sb)->dqptr_sem); - return QUOTA_OK; - } spin_lock(&dq_data_lock); for (cnt = 0; cnt < MAXQUOTAS; cnt++) { if (!inode->i_dquot[cnt]) @@ -1539,12 +1532,6 @@ int dquot_claim_space(struct inode *inode, qsize_t number) } down_read(&sb_dqopt(inode->i_sb)->dqptr_sem); - if (IS_NOQUOTA(inode)) { - up_read(&sb_dqopt(inode->i_sb)->dqptr_sem); - inode_claim_rsv_space(inode, number); - goto out; - } - spin_lock(&dq_data_lock); /* Claim reserved quotas to allocated quotas */ for (cnt = 0; cnt < MAXQUOTAS; cnt++) { @@ -1573,17 +1560,11 @@ int __dquot_free_space(struct inode *inode, qsize_t number, int reserve) /* First test before acquiring mutex - solves deadlocks when we * re-enter the quota code and are already holding the mutex */ if (IS_NOQUOTA(inode)) { -out_sub: inode_decr_space(inode, number, reserve); return QUOTA_OK; } down_read(&sb_dqopt(inode->i_sb)->dqptr_sem); - /* Now recheck reliably when holding dqptr_sem */ - if (IS_NOQUOTA(inode)) { - up_read(&sb_dqopt(inode->i_sb)->dqptr_sem); - goto out_sub; - } spin_lock(&dq_data_lock); for (cnt = 0; cnt < MAXQUOTAS; cnt++) { if (!inode->i_dquot[cnt]) @@ -1636,11 +1617,6 @@ int dquot_free_inode(const struct inode *inode, qsize_t number) return QUOTA_OK; down_read(&sb_dqopt(inode->i_sb)->dqptr_sem); - /* Now recheck reliably when holding dqptr_sem */ - if (IS_NOQUOTA(inode)) { - up_read(&sb_dqopt(inode->i_sb)->dqptr_sem); - return QUOTA_OK; - } spin_lock(&dq_data_lock); for (cnt = 0; cnt < MAXQUOTAS; cnt++) { if (!inode->i_dquot[cnt]) @@ -1692,7 +1668,6 @@ int dquot_transfer(struct inode *inode, struct iattr *iattr) GRPQUOTA); 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; @@ -2010,13 +1985,15 @@ static int vfs_load_quota_inode(struct inode *inode, int type, int format_id, /* We don't want quota and atime on quota files (deadlocks * possible) Also nobody should write to the file - we use * special IO operations which ignore the immutable bit. */ - down_write(&dqopt->dqptr_sem); mutex_lock_nested(&inode->i_mutex, I_MUTEX_QUOTA); oldflags = inode->i_flags & (S_NOATIME | S_IMMUTABLE | S_NOQUOTA); inode->i_flags |= S_NOQUOTA | S_NOATIME | S_IMMUTABLE; mutex_unlock(&inode->i_mutex); - up_write(&dqopt->dqptr_sem); + /* + * When S_NOQUOTA is set, remove dquot references as no more + * references can be added + */ sb->dq_op->drop(inode); } @@ -2053,14 +2030,12 @@ out_file_init: iput(inode); out_lock: if (oldflags != -1) { - down_write(&dqopt->dqptr_sem); mutex_lock_nested(&inode->i_mutex, I_MUTEX_QUOTA); /* Set the flags back (in the case of accidental quotaon() * on a wrong file we don't want to mess up the flags) */ inode->i_flags &= ~(S_NOATIME | S_NOQUOTA | S_IMMUTABLE); inode->i_flags |= oldflags; mutex_unlock(&inode->i_mutex); - up_write(&dqopt->dqptr_sem); } mutex_unlock(&dqopt->dqonoff_mutex); out_fmt: |