quota: atomic dq_flags operations in do_set_dqblk

PATCH In review Andrew Perepechko 2 participants 3 messages Apr 12, 2010 VFS

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Andrew Perepechko

author

2010-04-12 18:16 UTC #0 lore raw

PATCH 1/1 quota: atomic dq_flags operations in do_set_dqblk

From: Andrew Perepechko <[email protected]>

Non-atomic __set_bit calls are replaced with atomic set_bit calls in do_set_dqblk so that individual bits should not be lost in a possible race condition.

Signed-off-by Andrew Perepechko <[email protected]>

---

fs/dquot.c +6 -6

diff -puN fs/dquot.c fs/dquot.c
@@ -2065,32 +2065,32 @@ static int do_set_dqblk(struct dquot *dq
 	if (di->dqb_valid & QIF_SPACE) {
 		dm->dqb_curspace = di->dqb_curspace;
 		check_blim = 1;
-		__set_bit(DQ_LASTSET_B + QIF_SPACE_B, &dquot->dq_flags);
+		set_bit(DQ_LASTSET_B + QIF_SPACE_B, &dquot->dq_flags);
 	}
 	if (di->dqb_valid & QIF_BLIMITS) {
 		dm->dqb_bsoftlimit = qbtos(di->dqb_bsoftlimit);
 		dm->dqb_bhardlimit = qbtos(di->dqb_bhardlimit);
 		check_blim = 1;
-		__set_bit(DQ_LASTSET_B + QIF_BLIMITS_B, &dquot->dq_flags);
+		set_bit(DQ_LASTSET_B + QIF_BLIMITS_B, &dquot->dq_flags);
 	}
 	if (di->dqb_valid & QIF_INODES) {
 		dm->dqb_curinodes = di->dqb_curinodes;
 		check_ilim = 1;
-		__set_bit(DQ_LASTSET_B + QIF_INODES_B, &dquot->dq_flags);
+		set_bit(DQ_LASTSET_B + QIF_INODES_B, &dquot->dq_flags);
 	}
 	if (di->dqb_valid & QIF_ILIMITS) {
 		dm->dqb_isoftlimit = di->dqb_isoftlimit;
 		dm->dqb_ihardlimit = di->dqb_ihardlimit;
 		check_ilim = 1;
-		__set_bit(DQ_LASTSET_B + QIF_ILIMITS_B, &dquot->dq_flags);
+		set_bit(DQ_LASTSET_B + QIF_ILIMITS_B, &dquot->dq_flags);
 	}
 	if (di->dqb_valid & QIF_BTIME) {
 		dm->dqb_btime = di->dqb_btime;
-		__set_bit(DQ_LASTSET_B + QIF_BTIME_B, &dquot->dq_flags);
+		set_bit(DQ_LASTSET_B + QIF_BTIME_B, &dquot->dq_flags);
 	}
 	if (di->dqb_valid & QIF_ITIME) {
 		dm->dqb_itime = di->dqb_itime;
-		__set_bit(DQ_LASTSET_B + QIF_ITIME_B, &dquot->dq_flags);
+		set_bit(DQ_LASTSET_B + QIF_ITIME_B, &dquot->dq_flags);
 	}
 
 	if (check_blim) {

Jan Kara

reviewer

2010-04-12 19:09 UTC #1 lore raw

Quoted 4 lines · Andrew Perepechko

From: Andrew Perepechko <[email protected]>
Non-atomic __set_bit calls are replaced with atomic set_bit calls in do_set_dqblk so that individual bits should not be lost in a possible race condition.

I took a liberty of modifying the changelog to be more descriptive:

quota: Fix possible dq_flags corruption

dq_flags are modified non-atomically in do_set_dqblk via __set_bit calls and atomically for example in mark_dquot_dirty or clear_dquot_dirty. Hence a change done by an atomic operation can be overwritten by a change done by a non-atomic one. Fix the problem by using atomic bitops even in do_set_dqblk.

Otherwise I've merged the patch.

Honza

Quoted 44 lines

Signed-off-by Andrew Perepechko <[email protected]>

---
diff -puN fs/dquot.c fs/dquot.c

fs/dquot.c +6 -6

@@ -2065,32 +2065,32 @@ static int do_set_dqblk(struct dquot *dq
 	if (di->dqb_valid & QIF_SPACE) {
 		dm->dqb_curspace = di->dqb_curspace;
 		check_blim = 1;
-		__set_bit(DQ_LASTSET_B + QIF_SPACE_B, &dquot->dq_flags);
+		set_bit(DQ_LASTSET_B + QIF_SPACE_B, &dquot->dq_flags);
 	}
 	if (di->dqb_valid & QIF_BLIMITS) {
 		dm->dqb_bsoftlimit = qbtos(di->dqb_bsoftlimit);
 		dm->dqb_bhardlimit = qbtos(di->dqb_bhardlimit);
 		check_blim = 1;
-		__set_bit(DQ_LASTSET_B + QIF_BLIMITS_B, &dquot->dq_flags);
+		set_bit(DQ_LASTSET_B + QIF_BLIMITS_B, &dquot->dq_flags);
 	}
 	if (di->dqb_valid & QIF_INODES) {
 		dm->dqb_curinodes = di->dqb_curinodes;
 		check_ilim = 1;
-		__set_bit(DQ_LASTSET_B + QIF_INODES_B, &dquot->dq_flags);
+		set_bit(DQ_LASTSET_B + QIF_INODES_B, &dquot->dq_flags);
 	}
 	if (di->dqb_valid & QIF_ILIMITS) {
 		dm->dqb_isoftlimit = di->dqb_isoftlimit;
 		dm->dqb_ihardlimit = di->dqb_ihardlimit;
 		check_ilim = 1;
-		__set_bit(DQ_LASTSET_B + QIF_ILIMITS_B, &dquot->dq_flags);
+		set_bit(DQ_LASTSET_B + QIF_ILIMITS_B, &dquot->dq_flags);
 	}
 	if (di->dqb_valid & QIF_BTIME) {
 		dm->dqb_btime = di->dqb_btime;
-		__set_bit(DQ_LASTSET_B + QIF_BTIME_B, &dquot->dq_flags);
+		set_bit(DQ_LASTSET_B + QIF_BTIME_B, &dquot->dq_flags);
 	}
 	if (di->dqb_valid & QIF_ITIME) {
 		dm->dqb_itime = di->dqb_itime;
-		__set_bit(DQ_LASTSET_B + QIF_ITIME_B, &dquot->dq_flags);
+		set_bit(DQ_LASTSET_B + QIF_ITIME_B, &dquot->dq_flags);
 	}
 
 	if (check_blim) {

Signature · 2 lines

Jan Kara <[email protected]>
SUSE Labs, CR

Andrew Perepechko

author

2010-04-12 19:39 UTC #2 lore raw

Thanks a lot, Jan!

Andrew.

Quoted 84 lines · Jan Kara

Quoted 5 lines · Andrew Perepechko

From: Andrew Perepechko <[email protected]>
Non-atomic __set_bit calls are replaced with atomic set_bit calls in do_set_dqblk so that individual bits should not be lost in a possible race condition.

I took a liberty of modifying the changelog to be more descriptive:

quota: Fix possible dq_flags corruption

Otherwise I've merged the patch.

Honza

Quoted 63 lines

Signed-off-by Andrew Perepechko <[email protected]>

---
diff -puN fs/dquot.c fs/dquot.c

fs/dquot.c +6 -6

@@ -2065,32 +2065,32 @@ static int do_set_dqblk(struct dquot *dq
 
 	if (di->dqb_valid & QIF_SPACE) {
 
 		dm->dqb_curspace = di->dqb_curspace;
 		check_blim = 1;
 
-		__set_bit(DQ_LASTSET_B + QIF_SPACE_B, &dquot->dq_flags);
+		set_bit(DQ_LASTSET_B + QIF_SPACE_B, &dquot->dq_flags);
 
 	}
 	if (di->dqb_valid & QIF_BLIMITS) {
 
 		dm->dqb_bsoftlimit = qbtos(di->dqb_bsoftlimit);
 		dm->dqb_bhardlimit = qbtos(di->dqb_bhardlimit);
 		check_blim = 1;
 
-		__set_bit(DQ_LASTSET_B + QIF_BLIMITS_B, &dquot->dq_flags);
+		set_bit(DQ_LASTSET_B + QIF_BLIMITS_B, &dquot->dq_flags);
 
 	}
 	if (di->dqb_valid & QIF_INODES) {
 
 		dm->dqb_curinodes = di->dqb_curinodes;
 		check_ilim = 1;
 
-		__set_bit(DQ_LASTSET_B + QIF_INODES_B, &dquot->dq_flags);
+		set_bit(DQ_LASTSET_B + QIF_INODES_B, &dquot->dq_flags);
 
 	}
 	if (di->dqb_valid & QIF_ILIMITS) {
 
 		dm->dqb_isoftlimit = di->dqb_isoftlimit;
 		dm->dqb_ihardlimit = di->dqb_ihardlimit;
 		check_ilim = 1;
 
-		__set_bit(DQ_LASTSET_B + QIF_ILIMITS_B, &dquot->dq_flags);
+		set_bit(DQ_LASTSET_B + QIF_ILIMITS_B, &dquot->dq_flags);
 
 	}
 	if (di->dqb_valid & QIF_BTIME) {
 
 		dm->dqb_btime = di->dqb_btime;
 
-		__set_bit(DQ_LASTSET_B + QIF_BTIME_B, &dquot->dq_flags);
+		set_bit(DQ_LASTSET_B + QIF_BTIME_B, &dquot->dq_flags);
 
 	}
 	if (di->dqb_valid & QIF_ITIME) {
 
 		dm->dqb_itime = di->dqb_itime;
 
-		__set_bit(DQ_LASTSET_B + QIF_ITIME_B, &dquot->dq_flags);
+		set_bit(DQ_LASTSET_B + QIF_ITIME_B, &dquot->dq_flags);
 
 	}
 
 	if (check_blim) {