From 966997992bdbd5fffc632bf705678e287ed50bf7 Mon Sep 17 00:00:00 2001 From: Venkatesh Somyajulu Date: Fri, 25 Jul 2014 17:21:04 +0530 Subject: cluster/dht: Modified logic of linkto file deletion on non-hashed Currently whenever dht_lookup_everywhere gets called, if in dht_lookup_everywhere_cbk, a linkto file is found on non-hashed subvolume, file is unlinked. But there are cases when this file is under migration. Under such condition, we should avoid deletion of file. When some other rebalance process changes the layout of parent such that dst_file (w.r.t. migration) falls on non-hashed node, then may be lookup could have found it as linkto file but just before unlink, file is under migration or already migrated In such cased unlink can be avoided. Race: ------- If we have two bricks (brick-1 and brick-2) with initial file "a" under BaseDir which is hashed as well as cached on (brick-1). Assume "a" hashing gives 44. Brick-1 Brick-2 Initial Setup: BaseDir/a BaseDir [1-50] [51-100] Now add new-brick Brick-3. 1. Rebalance-1 on node Node-1 (Brick-1 node) will reset the BaseDir Layout. 2. After that it will perform a) Create linkto file on new-hashed (brick-2) b) Perform file migration. 1.Rebalance-1 Fixes the base-layout: Brick-1 Brick-2 Brick-3 --------- ---------- ------------ BaseDir/a BaseDir BaseDir [1-33] [34-66] [67-100] 2. Only a) is BaseDir/a BaseDir/a(linkto) BaseDir performed Create linktofile Now rebalance 2 on node-2 jumped in and it will perform step 1 and 2-a. After (rebal-2, step-1), it changes the layout of the BaseDir. BaseDir/a BaseDir/a(link) BaseDir [67-100] [1-33] [34-66] For (rebale-2, step-2), It will perform lookup at Brick-3 as w.r.t new layout 44 falls for brick-3. But lookup will fail. So dht_lookup_everywhere gets called. NOTE: On brick-2 by rebalance-1, a linkto file was created. Currently that linkto files gets deleted by rebalance-2 lookup as it is considered as stale linkto file. But with patch if rebalance is already in progress or rebalance is over, linkto file will not be unlinked. If rebalance is in progress fd will be open and if rebalance is over then linkto file wont be set. Change-Id: I3fee0d28de3c76197325536a9e30099d2413f079 BUG: 1116150 Signed-off-by: Venkatesh Somyajulu Reviewed-on: http://review.gluster.org/8345 Tested-by: Gluster Build System Reviewed-by: Raghavendra G Reviewed-by: Shyamsundar Ranganathan Reviewed-by: Vijay Bellur --- xlators/storage/posix/src/posix.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'xlators/storage/posix') diff --git a/xlators/storage/posix/src/posix.c b/xlators/storage/posix/src/posix.c index 16188a23694..5decac295ff 100644 --- a/xlators/storage/posix/src/posix.c +++ b/xlators/storage/posix/src/posix.c @@ -1399,7 +1399,7 @@ posix_unlink (call_frame_t *frame, xlator_t *this, priv = this->private; - op_ret = dict_get_int32 (xdata, "dont-unlink-for-open-fd", + op_ret = dict_get_int32 (xdata, DHT_SKIP_OPEN_FD_UNLINK, &check_open_fd); if (!op_ret && check_open_fd) { @@ -1420,7 +1420,7 @@ posix_unlink (call_frame_t *frame, xlator_t *this, } - op_ret = dict_get_int32 (xdata, "unlink-only-if-dht-linkto-file", + op_ret = dict_get_int32 (xdata, DHT_SKIP_NON_LINKTO_UNLINK, &unlink_if_linkto); if (!op_ret && unlink_if_linkto) { -- cgit