From a7356806f9f7c148d4e0a972f6a418d1ca82bcd0 Mon Sep 17 00:00:00 2001 From: Jeff Darcy Date: Tue, 8 Jul 2014 21:56:04 -0400 Subject: dht: fix rename race If two clients try to rename the same file at the same time, we sometimes end up with *no file at all* in either the old or new location. That's kind of bad. The culprit seems to be some overly aggressive cleanup code. AFAICT, based on today's study of the code, the intent of the changed section is to remove any linkfile we might have created before the actual rename. However, what we're removing might not be our extra link. If we're racing with another client that's also doing a rename, it might be the only remaining link to the user's data. The solution, which is good enough to pass this test but almost certainly still not complete, is to be more selective about when we do this unlink. Now, we only do it if we know that, at some point, we did in fact create the link without error (notably ENOENT on the source or EEXIST on the destination) ourselves. Change-Id: I8d8cce150b6f8b372c9fb813c90be58d69f8eb7b BUG: 1139988 Signed-off-by: Jeff Darcy Reviewed-on: http://review.gluster.org/8269 Tested-by: Gluster Build System Reviewed-by: Vijay Bellur Reviewed-on: http://review.gluster.org/8672 Reviewed-by: Raghavendra G Reviewed-by: Kaleb KEITHLEY --- xlators/cluster/dht/src/dht-common.h | 1 + xlators/cluster/dht/src/dht-rename.c | 18 ++++++++++++++---- 2 files changed, 15 insertions(+), 4 deletions(-) (limited to 'xlators') diff --git a/xlators/cluster/dht/src/dht-common.h b/xlators/cluster/dht/src/dht-common.h index 49fbd3878a0..83725f09712 100644 --- a/xlators/cluster/dht/src/dht-common.h +++ b/xlators/cluster/dht/src/dht-common.h @@ -183,6 +183,7 @@ struct dht_local { struct dht_rebalance_ rebalance; xlator_t *first_up_subvol; + gf_boolean_t added_link; }; typedef struct dht_local dht_local_t; diff --git a/xlators/cluster/dht/src/dht-rename.c b/xlators/cluster/dht/src/dht-rename.c index 35fedeaa7a4..7685ad88427 100644 --- a/xlators/cluster/dht/src/dht-rename.c +++ b/xlators/cluster/dht/src/dht-rename.c @@ -378,8 +378,9 @@ dht_rename_cleanup (call_frame_t *frame) if (dst_hashed != src_hashed && dst_hashed != src_cached) call_cnt++; - if (src_cached != dst_hashed) + if (local->added_link && (src_cached != dst_hashed)) { call_cnt++; + } local->call_cnt = call_cnt; @@ -395,10 +396,11 @@ dht_rename_cleanup (call_frame_t *frame) &local->loc, 0, NULL); } - if (src_cached != dst_hashed) { + if (local->added_link && (src_cached != dst_hashed)) { gf_log (this->name, GF_LOG_TRACE, "unlinking link %s => %s (%s)", local->loc.path, local->loc2.path, src_cached->name); + STACK_WIND (frame, dht_rename_unlink_cbk, src_cached, src_cached->fops->unlink, &local->loc2, 0, NULL); @@ -652,9 +654,15 @@ dht_rename_links_cbk (call_frame_t *frame, void *cookie, xlator_t *this, "link/file on %s failed (%s)", prev->this->name, strerror (op_errno)); local->op_ret = -1; - if (op_errno != ENOENT) + if (op_errno != ENOENT) { local->op_errno = op_errno; - } else { + + if (prev->this == local->src_cached) { + local->added_link = _gf_false; + } + } + } else if (local->src_cached == prev->this) { + /* merge of attr returned only from linkfile creation */ dht_iatt_merge (this, &local->stbuf, stbuf, prev->this); } @@ -767,6 +775,8 @@ dht_rename_create_links (call_frame_t *frame) gf_log (this->name, GF_LOG_TRACE, "link %s => %s (%s)", local->loc.path, local->loc2.path, src_cached->name); + + local->added_link = _gf_true; STACK_WIND (frame, dht_rename_links_cbk, src_cached, src_cached->fops->link, &local->loc, &local->loc2, NULL); -- cgit