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-rw-r--r--xlators/cluster/afr/src/afr-common.c57
1 files changed, 57 insertions, 0 deletions
diff --git a/xlators/cluster/afr/src/afr-common.c b/xlators/cluster/afr/src/afr-common.c
index d3e5182..cefbaa8 100644
--- a/xlators/cluster/afr/src/afr-common.c
+++ b/xlators/cluster/afr/src/afr-common.c
@@ -1818,6 +1818,57 @@ out:
return;
}
+gf_boolean_t
+afr_is_entry_possibly_under_creation (afr_local_t *local, xlator_t *this)
+{
+ /*
+ * We need to perform this test in lookup done and treat on going
+ * create/DELETE as ENOENT.
+ * Reason:
+ Multiple clients A, B and C are attempting 'mkdir -p /mnt/a/b/c'
+
+ 1 Client A is in the middle of mkdir(/a). It has acquired lock.
+ It has performed mkdir(/a) on one subvol, and second one is still
+ in progress
+ 2 Client B performs a lookup, sees directory /a on one,
+ ENOENT on the other, succeeds lookup.
+ 3 Client B performs lookup on /a/b on both subvols, both return ENOENT
+ (one subvol because /a/b does not exist, another because /a
+ itself does not exist)
+ 4 Client B proceeds to mkdir /a/b. It obtains entrylk on inode=/a with
+ basename=b on one subvol, but fails on other subvol as /a is yet to
+ be created by Client A.
+ 5 Client A finishes mkdir of /a on other subvol
+ 6 Client C also attempts to create /a/b, lookup returns ENOENT on
+ both subvols.
+ 7 Client C tries to obtain entrylk on on inode=/a with basename=b,
+ obtains on one subvol (where B had failed), and waits for B to unlock
+ on other subvol.
+ 8 Client B finishes mkdir() on one subvol with GFID-1 and completes
+ transaction and unlocks
+ 9 Client C gets the lock on the second subvol, At this stage second
+ subvol already has /a/b created from Client B, but Client C does not
+ check that in the middle of mkdir transaction
+ 10 Client C attempts mkdir /a/b on both subvols. It succeeds on
+ ONLY ONE (where Client B could not get lock because of
+ missing parent /a dir) with GFID-2, and gets EEXIST from ONE subvol.
+ This way we have /a/b in GFID mismatch. One subvol got GFID-1 because
+ Client B performed transaction on only one subvol (because entrylk()
+ could not be obtained on second subvol because of missing parent dir --
+ caused by premature/speculative succeeding of lookup() on /a when locks
+ are detected). Other subvol gets GFID-2 from Client C because while
+ it was waiting for entrylk() on both subvols, Client B was in the
+ middle of creating mkdir() on only one subvol, and Client C does not
+ "expect" this when it is between lock() and pre-op()/op() phase of the
+ transaction.
+ */
+ if (local->cont.lookup.parent_entrylk && local->enoent_count)
+ return _gf_true;
+
+ return _gf_false;
+}
+
+
static void
afr_lookup_done (call_frame_t *frame, xlator_t *this)
{
@@ -1834,6 +1885,12 @@ afr_lookup_done (call_frame_t *frame, xlator_t *this)
priv = this->private;
local = frame->local;
+ if (afr_is_entry_possibly_under_creation (local, this)) {
+ local->op_ret = -1;
+ local->op_errno = ENOENT;
+ goto unwind;
+ }
+
if (local->op_ret < 0)
goto unwind;