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quota: Prevent memory allocation recursion while holding dq_lock

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As described in commit 02117b8ae9 ("f2fs: Set GF_NOFS in
read_cache_page_gfp while doing f2fs_quota_read"), we must not enter
filesystem reclaim while holding the dq_lock.  Prevent this more generally
by using memalloc_nofs_save() while holding the lock.

Link: https://lore.kernel.org/r/20220605143815.2330891-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Matthew Wilcox (Oracle) 2022-06-05 15:38:13 +01:00 committed by Jan Kara
parent 10e1407310
commit 537e11cdc7
1 changed files with 10 additions and 0 deletions
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10
fs/quota/dquot.c
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@ -79,6 +79,7 @@
#include <linux/capability.h>
#include <linux/quotaops.h>
#include <linux/blkdev.h>
#include <linux/sched/mm.h>
#include "../internal.h" /* ugh */
#include <linux/uaccess.h>
@ -425,9 +426,11 @@ EXPORT_SYMBOL(mark_info_dirty);
int dquot_acquire(struct dquot *dquot)
{
int ret = 0, ret2 = 0;
unsigned int memalloc;
struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);
mutex_lock(&dquot->dq_lock);
memalloc = memalloc_nofs_save();
if (!test_bit(DQ_READ_B, &dquot->dq_flags)) {
ret = dqopt->ops[dquot->dq_id.type]->read_dqblk(dquot);
if (ret < 0)
@ -458,6 +461,7 @@ int dquot_acquire(struct dquot *dquot)
smp_mb__before_atomic();
set_bit(DQ_ACTIVE_B, &dquot->dq_flags);
out_iolock:
memalloc_nofs_restore(memalloc);
mutex_unlock(&dquot->dq_lock);
return ret;
}
@ -469,9 +473,11 @@ EXPORT_SYMBOL(dquot_acquire);
int dquot_commit(struct dquot *dquot)
{
int ret = 0;
unsigned int memalloc;
struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);
mutex_lock(&dquot->dq_lock);
memalloc = memalloc_nofs_save();
if (!clear_dquot_dirty(dquot))
goto out_lock;
/* Inactive dquot can be only if there was error during read/init
@ -481,6 +487,7 @@ int dquot_commit(struct dquot *dquot)
else
ret = -EIO;
out_lock:
memalloc_nofs_restore(memalloc);
mutex_unlock(&dquot->dq_lock);
return ret;
}
@ -492,9 +499,11 @@ EXPORT_SYMBOL(dquot_commit);
int dquot_release(struct dquot *dquot)
{
int ret = 0, ret2 = 0;
unsigned int memalloc;
struct quota_info *dqopt = sb_dqopt(dquot->dq_sb);
mutex_lock(&dquot->dq_lock);
memalloc = memalloc_nofs_save();
/* Check whether we are not racing with some other dqget() */
if (dquot_is_busy(dquot))
goto out_dqlock;
@ -510,6 +519,7 @@ int dquot_release(struct dquot *dquot)
}
clear_bit(DQ_ACTIVE_B, &dquot->dq_flags);
out_dqlock:
memalloc_nofs_restore(memalloc);
mutex_unlock(&dquot->dq_lock);
return ret;
}