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authorBrian Foster <bfoster@redhat.com>2018-07-24 13:43:09 -0700
committerDarrick J. Wong <darrick.wong@oracle.com>2018-07-26 10:15:12 -0700
commit03f4e4b26cd5f6eed728f82d90039a19d1b51ce3 (patch)
treed0f08d48590568df7cea64eb92fdf478ab010d98 /fs/xfs
parentdcbd44f79986e55691600b969c14db004d741883 (diff)
downloadlinux-03f4e4b26cd5f6eed728f82d90039a19d1b51ce3.tar.bz2
xfs: make deferred processing safe for embedded dfops
xfs_defer_finish() has a couple quirks that are not safe with respect to the upcoming internal dfops functionality. First, xfs_defer_finish() attaches the passed in dfops structure to ->t_dfops and caches and restores the original value. Second, it continues to use the initial dfops reference before and after the transaction roll. These behaviors assume that dop is an independent memory allocation from the transaction itself, which may not always be true once transactions begin to use an embedded dfops structure. In the latter model, dfops processing creates a new xfs_defer_ops structure with each transaction and the associated state is migrated across to the new transaction. Fix up xfs_defer_finish() to handle the possibility of the current dfops changing after a transaction roll. Since ->t_dfops is used unconditionally in this path, it is no longer necessary to attach/restore ->t_dfops and pass it explicitly down to xfs_defer_trans_roll(). Update dop in the latter function and the caller to ensure that it always refers to the current dfops structure. Signed-off-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Bill O'Donnell <billodo@redhat.com> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Diffstat (limited to 'fs/xfs')
-rw-r--r--fs/xfs/libxfs/xfs_defer.c32
1 files changed, 14 insertions, 18 deletions
diff --git a/fs/xfs/libxfs/xfs_defer.c b/fs/xfs/libxfs/xfs_defer.c
index c4b0eaeb5190..ee734a8b3fa9 100644
--- a/fs/xfs/libxfs/xfs_defer.c
+++ b/fs/xfs/libxfs/xfs_defer.c
@@ -225,9 +225,9 @@ xfs_defer_trans_abort(
/* Roll a transaction so we can do some deferred op processing. */
STATIC int
xfs_defer_trans_roll(
- struct xfs_trans **tp,
- struct xfs_defer_ops *dop)
+ struct xfs_trans **tp)
{
+ struct xfs_defer_ops *dop = (*tp)->t_dfops;
int i;
int error;
@@ -243,6 +243,7 @@ xfs_defer_trans_roll(
/* Roll the transaction. */
error = xfs_trans_roll(tp);
+ dop = (*tp)->t_dfops;
if (error) {
trace_xfs_defer_trans_roll_error((*tp)->t_mountp, dop, error);
xfs_defer_trans_abort(*tp, dop, error);
@@ -338,31 +339,25 @@ xfs_defer_finish(
void *state;
int error = 0;
void (*cleanup_fn)(struct xfs_trans *, void *, int);
- struct xfs_defer_ops *orig_dop;
ASSERT((*tp)->t_flags & XFS_TRANS_PERM_LOG_RES);
+ ASSERT((*tp)->t_dfops == dop);
trace_xfs_defer_finish((*tp)->t_mountp, dop, _RET_IP_);
- /*
- * Attach dfops to the transaction during deferred ops processing. This
- * explicitly causes calls into the allocator to defer AGFL block frees.
- * Note that this code can go away once all dfops users attach to the
- * associated tp.
- */
- ASSERT(!(*tp)->t_dfops || ((*tp)->t_dfops == dop));
- orig_dop = (*tp)->t_dfops;
- (*tp)->t_dfops = dop;
-
/* Until we run out of pending work to finish... */
while (xfs_defer_has_unfinished_work(dop)) {
/* Log intents for work items sitting in the intake. */
xfs_defer_intake_work(*tp, dop);
- /* Roll the transaction. */
- error = xfs_defer_trans_roll(tp, dop);
+ /*
+ * Roll the transaction and update dop in case dfops was
+ * embedded in the transaction.
+ */
+ error = xfs_defer_trans_roll(tp);
if (error)
goto out;
+ dop = (*tp)->t_dfops;
/* Log an intent-done item for the first pending item. */
dfp = list_first_entry(&dop->dop_pending,
@@ -428,10 +423,11 @@ xfs_defer_finish(
* Roll the transaction once more to avoid returning to the caller
* with a dirty transaction.
*/
- if ((*tp)->t_flags & XFS_TRANS_DIRTY)
- error = xfs_defer_trans_roll(tp, dop);
+ if ((*tp)->t_flags & XFS_TRANS_DIRTY) {
+ error = xfs_defer_trans_roll(tp);
+ dop = (*tp)->t_dfops;
+ }
out:
- (*tp)->t_dfops = orig_dop;
if (error)
trace_xfs_defer_finish_error((*tp)->t_mountp, dop, error);
else