The patch titled
Subject: nilfs2: fix timing issue between rmcp and chcp ioctls
has been added to the -mm tree. Its filename is
nilfs2-fix-timing-issue-between-rmcp-and-chcp-ioctls.patch
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From: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxxxxxx>
Subject: nilfs2: fix timing issue between rmcp and chcp ioctls
The checkpoint deletion ioctl (rmcp ioctl) has potential for breaking
snapshot because it is not fully exclusive with checkpoint mode change
ioctl (chcp ioctl).
The rmcp ioctl first tests if the specified checkpoint is a snapshot or
not within nilfs_cpfile_delete_checkpoint function, and then calls
nilfs_cpfile_delete_checkpoints function to actually invalidate the
checkpoint only if it's not a snapshot. However, the checkpoint can be
changed into a snapshot by the chcp ioctl between these two operations.
In that case, calling nilfs_cpfile_delete_checkpoints() wrongly
invalidates the snapshot, which leads to snapshot list corruption and
snapshot count mismatch.
This fixes the issue by changing nilfs_cpfile_delete_checkpoints() so that
it reconfirms the target checkpoints are snapshot or not.
This second check is exclusive with the chcp operation since it is
protected by an existing semaphore.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxxxxxx>
Cc: Fernando Luis Vazquez Cao <fernando@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/nilfs2/cpfile.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff -puN fs/nilfs2/cpfile.c~nilfs2-fix-timing-issue-between-rmcp-and-chcp-ioctls fs/nilfs2/cpfile.c
--- a/fs/nilfs2/cpfile.c~nilfs2-fix-timing-issue-between-rmcp-and-chcp-ioctls
+++ a/fs/nilfs2/cpfile.c
@@ -286,7 +286,7 @@ int nilfs_cpfile_delete_checkpoints(stru
__u64 cno;
void *kaddr;
unsigned long tnicps;
- int ret, ncps, nicps, count, i;
+ int ret, ncps, nicps, nss, count, i;
if (unlikely(start == 0 || start > end)) {
printk(KERN_ERR "%s: invalid range of checkpoint numbers: "
@@ -301,6 +301,7 @@ int nilfs_cpfile_delete_checkpoints(stru
if (ret < 0)
goto out_sem;
tnicps = 0;
+ nss = 0;
for (cno = start; cno < end; cno += ncps) {
ncps = nilfs_cpfile_checkpoints_in_block(cpfile, cno, end);
@@ -318,8 +319,9 @@ int nilfs_cpfile_delete_checkpoints(stru
cpfile, cno, cp_bh, kaddr);
nicps = 0;
for (i = 0; i < ncps; i++, cp = (void *)cp + cpsz) {
- WARN_ON(nilfs_checkpoint_snapshot(cp));
- if (!nilfs_checkpoint_invalid(cp)) {
+ if (nilfs_checkpoint_snapshot(cp)) {
+ nss++;
+ } else if (!nilfs_checkpoint_invalid(cp)) {
nilfs_checkpoint_set_invalid(cp);
nicps++;
}
@@ -364,6 +366,8 @@ int nilfs_cpfile_delete_checkpoints(stru
}
brelse(header_bh);
+ if (nss > 0)
+ ret = -EBUSY;
out_sem:
up_write(&NILFS_MDT(cpfile)->mi_sem);
_
Subject: Subject: nilfs2: fix timing issue between rmcp and chcp ioctls
Patches currently in -mm which might be from konishi.ryusuke@xxxxxxxxxxxxx are
nilfs2-add-omitted-comment-for-ns_mount_state-field-of-the_nilfs-structure.patch
nilfs2-remove-references-to-long-gone-super-operations.patch
nilfs2-fix-timing-issue-between-rmcp-and-chcp-ioctls.patch
nilfs2-fix-deadlock-issue-between-chcp-and-thaw-ioctls.patch
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