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| author | Dmitry Monakhov <dmtrmonakhov@yandex-team.ru> | 2019-10-31 10:39:20 +0000 |
|---|---|---|
| committer | Jan Kara <jack@suse.cz> | 2019-10-31 19:07:42 +0100 |
| commit | df4bb5d128e2c44848aeb36b7ceceba3ac85080d (patch) | |
| tree | a45954c3bb978dbf2aa7de092b3e5c53adc95dfd | |
| parent | 6ff33d99fc5c96797103b48b7b0902c296f09c05 (diff) | |
| download | linux-df4bb5d128e2c44848aeb36b7ceceba3ac85080d.tar.gz linux-df4bb5d128e2c44848aeb36b7ceceba3ac85080d.tar.bz2 linux-df4bb5d128e2c44848aeb36b7ceceba3ac85080d.zip | |
quota: Check that quota is not dirty before release
There is a race window where quota was redirted once we drop dq_list_lock inside dqput(),
but before we grab dquot->dq_lock inside dquot_release()
TASK1 TASK2 (chowner)
->dqput()
we_slept:
spin_lock(&dq_list_lock)
if (dquot_dirty(dquot)) {
spin_unlock(&dq_list_lock);
dquot->dq_sb->dq_op->write_dquot(dquot);
goto we_slept
if (test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) {
spin_unlock(&dq_list_lock);
dquot->dq_sb->dq_op->release_dquot(dquot);
dqget()
mark_dquot_dirty()
dqput()
goto we_slept;
}
So dquot dirty quota will be released by TASK1, but on next we_sleept loop
we detect this and call ->write_dquot() for it.
XFSTEST: https://github.com/dmonakhov/xfstests/commit/440a80d4cbb39e9234df4d7240aee1d551c36107
Link: https://lore.kernel.org/r/20191031103920.3919-2-dmonakhov@openvz.org
CC: stable@vger.kernel.org
Signed-off-by: Dmitry Monakhov <dmtrmonakhov@yandex-team.ru>
Signed-off-by: Jan Kara <jack@suse.cz>
| -rw-r--r-- | fs/ocfs2/quota_global.c | 2 | ||||
| -rw-r--r-- | fs/quota/dquot.c | 2 | ||||
| -rw-r--r-- | include/linux/quotaops.h | 10 |
3 files changed, 12 insertions, 2 deletions
diff --git a/fs/ocfs2/quota_global.c b/fs/ocfs2/quota_global.c index 7a922190a8c7..eda83487c9ec 100644 --- a/fs/ocfs2/quota_global.c +++ b/fs/ocfs2/quota_global.c @@ -728,7 +728,7 @@ static int ocfs2_release_dquot(struct dquot *dquot) mutex_lock(&dquot->dq_lock); /* Check whether we are not racing with some other dqget() */ - if (atomic_read(&dquot->dq_count) > 1) + if (dquot_is_busy(dquot)) goto out; /* Running from downconvert thread? Postpone quota processing to wq */ if (current == osb->dc_task) { diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c index b492b9ea829a..72d24a5451bb 100644 --- a/fs/quota/dquot.c +++ b/fs/quota/dquot.c @@ -497,7 +497,7 @@ int dquot_release(struct dquot *dquot) mutex_lock(&dquot->dq_lock); /* Check whether we are not racing with some other dqget() */ - if (atomic_read(&dquot->dq_count) > 1) + if (dquot_is_busy(dquot)) goto out_dqlock; if (dqopt->ops[dquot->dq_id.type]->release_dqblk) { ret = dqopt->ops[dquot->dq_id.type]->release_dqblk(dquot); diff --git a/include/linux/quotaops.h b/include/linux/quotaops.h index 185d94829701..91e0b7624053 100644 --- a/include/linux/quotaops.h +++ b/include/linux/quotaops.h @@ -54,6 +54,16 @@ static inline struct dquot *dqgrab(struct dquot *dquot) atomic_inc(&dquot->dq_count); return dquot; } + +static inline bool dquot_is_busy(struct dquot *dquot) +{ + if (test_bit(DQ_MOD_B, &dquot->dq_flags)) + return true; + if (atomic_read(&dquot->dq_count) > 1) + return true; + return false; +} + void dqput(struct dquot *dquot); int dquot_scan_active(struct super_block *sb, int (*fn)(struct dquot *dquot, unsigned long priv), |