+++ This bug was initially created as a clone of Bug #967717 +++ Description of problem: At the moment data-self-heal acquires locks in following pattern. It takes full file lock then gets xattrs on files on both replicas. Decides sources/sinks based on the xattrs. Now it acquires lock from 0-128k then unlocks the full file lock. Syncs 0-128k range from source to sink now acquires lock 128k+1 till 256k then unlocks 0-128k, syncs 128k+1 till 256k block... so on finally it takes full file lock again then unlocks the final small range block. It decrements pending counts and then unlocks the full file lock. This pattern of locks is chosen to avoid more than 1 self-heal to be in progress. BUT if another self-heal tries to take a full file lock while a self-heal is already in progress it will be put in blocked queue, further inodelks from writes by the application will also be put in blocked queue because of the way locks xlator grants inodelks. So until the self-heal is complete writes are blocked. Here is the code: xlators/features/locks/src/inodelk.c - line 225 if (__blocked_lock_conflict (dom, lock) && !(__owner_has_lock (dom, lock))) { ret = -EAGAIN; if (can_block == 0) goto out; gettimeofday (&lock->blkd_time, NULL); list_add_tail (&lock->blocked_locks, &dom->blocked_inodelks); } This leads to hangs in applications. Version-Release number of selected component (if applicable): How reproducible: Steps to Reproduce: 1. 2. 3. Actual results: Expected results: Additional info: --- Additional comment from Anand Avati on 2013-05-28 04:18:58 EDT --- REVIEW: http://review.gluster.org/5099 (cluster/afr: Refactor inodelk to handle multiple domains) posted (#1) for review on master by Pranith Kumar Karampuri (pkarampu) --- Additional comment from Anand Avati on 2013-05-28 04:19:20 EDT --- REVIEW: http://review.gluster.org/5100 (cluster/afr: Let two data-self-heals compete in new domain) posted (#1) for review on master by Pranith Kumar Karampuri (pkarampu) --- Additional comment from Anand Avati on 2013-05-28 04:32:54 EDT --- REVIEW: http://review.gluster.org/5099 (cluster/afr: Refactor inodelk to handle multiple domains) posted (#2) for review on master by Pranith Kumar Karampuri (pkarampu) --- Additional comment from Anand Avati on 2013-05-28 04:33:15 EDT --- REVIEW: http://review.gluster.org/5100 (cluster/afr: Let two data-self-heals compete in new domain) posted (#2) for review on master by Pranith Kumar Karampuri (pkarampu) --- Additional comment from Anand Avati on 2013-05-28 05:14:34 EDT --- REVIEW: http://review.gluster.org/5099 (cluster/afr: Refactor inodelk to handle multiple domains) posted (#3) for review on master by Pranith Kumar Karampuri (pkarampu) --- Additional comment from Anand Avati on 2013-05-28 05:14:56 EDT --- REVIEW: http://review.gluster.org/5100 (cluster/afr: Let two data-self-heals compete in new domain) posted (#3) for review on master by Pranith Kumar Karampuri (pkarampu) --- Additional comment from Anand Avati on 2013-05-31 03:41:01 EDT --- REVIEW: http://review.gluster.org/5099 (cluster/afr: Refactor inodelk to handle multiple domains) posted (#4) for review on master by Pranith Kumar Karampuri (pkarampu) --- Additional comment from Anand Avati on 2013-05-31 03:41:23 EDT --- REVIEW: http://review.gluster.org/5100 (cluster/afr: Let two data-self-heals compete in new domain) posted (#4) for review on master by Pranith Kumar Karampuri (pkarampu) --- Additional comment from Anand Avati on 2013-06-18 03:32:03 EDT --- REVIEW: http://review.gluster.org/5099 (cluster/afr: Refactor inodelk to handle multiple domains) posted (#5) for review on master by Pranith Kumar Karampuri (pkarampu) --- Additional comment from Anand Avati on 2013-06-18 03:32:29 EDT --- REVIEW: http://review.gluster.org/5100 (cluster/afr: Let two data-self-heals compete in new domain) posted (#5) for review on master by Pranith Kumar Karampuri (pkarampu) --- Additional comment from Anand Avati on 2013-06-25 22:53:40 EDT --- REVIEW: http://review.gluster.org/5099 (cluster/afr: Refactor inodelk to handle multiple domains) posted (#6) for review on master by Pranith Kumar Karampuri (pkarampu) --- Additional comment from Anand Avati on 2013-06-25 22:54:04 EDT --- REVIEW: http://review.gluster.org/5100 (cluster/afr: Let two data-self-heals compete in new domain) posted (#6) for review on master by Pranith Kumar Karampuri (pkarampu) --- Additional comment from Anand Avati on 2013-07-03 12:59:43 EDT --- REVIEW: http://review.gluster.org/5099 (cluster/afr: Refactor inodelk to handle multiple domains) posted (#7) for review on master by Pranith Kumar Karampuri (pkarampu) --- Additional comment from Anand Avati on 2013-07-03 13:00:07 EDT --- REVIEW: http://review.gluster.org/5100 (cluster/afr: Let two data-self-heals compete in new domain) posted (#7) for review on master by Pranith Kumar Karampuri (pkarampu) --- Additional comment from Anand Avati on 2013-07-03 20:49:32 EDT --- REVIEW: http://review.gluster.org/5099 (cluster/afr: Refactor inodelk to handle multiple domains) posted (#8) for review on master by Pranith Kumar Karampuri (pkarampu) --- Additional comment from Anand Avati on 2013-07-03 20:49:56 EDT --- REVIEW: http://review.gluster.org/5100 (cluster/afr: Let two data-self-heals compete in new domain) posted (#8) for review on master by Pranith Kumar Karampuri (pkarampu) --- Additional comment from Anand Avati on 2013-07-04 00:28:55 EDT --- COMMIT: http://review.gluster.org/5099 committed in master by Vijay Bellur (vbellur) ------ commit c2abf3a6e39c5a5832a165757483bc0ae23cdb63 Author: Pranith Kumar K <pkarampu> Date: Wed Jul 3 21:21:48 2013 +0530 cluster/afr: Refactor inodelk to handle multiple domains - afr_local_copy should not be memduping locked nodes, that would mean that lock is taken in self-heal on those nodes even before it actually takes the lock. So removed memdup code. Even entry lock related copying (lockee info) is also not necessary for self-heal functionality, so removing that as well. Since it is not local_copy anymore changed its name. - My editor changed tabs to spaces. Change-Id: I8dfb92cb8338e9a967c06907a8e29a8404782d61 BUG: 967717 Signed-off-by: Pranith Kumar K <pkarampu> Reviewed-on: http://review.gluster.org/5099 Tested-by: Gluster Build System <jenkins.com> Reviewed-by: Vijay Bellur <vbellur> --- Additional comment from Anand Avati on 2013-07-04 00:36:06 EDT --- COMMIT: http://review.gluster.org/5100 committed in master by Vijay Bellur (vbellur) ------ commit 0aa4248cf967b158c0cf6ce33c300ad4b3ee3249 Author: Pranith Kumar K <pkarampu> Date: Wed Jul 3 21:28:25 2013 +0530 cluster/afr: Let two data-self-heals compete in new domain Problem: At the moment data-self-heal acquires locks in following pattern. It takes full file lock then gets xattrs on files on both replicas. Decides sources/sinks based on the xattrs. Now it acquires lock from 0-128k then unlocks the full file lock. Syncs 0-128k range from source to sink now acquires lock 128k+1 till 256k then unlocks 0-128k, syncs 128k+1 till 256k block... so on finally it takes full file lock again then unlocks the final small range block. It decrements pending counts and then unlocks the full file lock. This pattern of locks is chosen to avoid more than 1 self-heal to be in progress. BUT if another self-heal tries to take a full file lock while a self-heal is already in progress it will be put in blocked queue, further inodelks from writes by the application will also be put in blocked queue because of the way locks xlator grants inodelks. So until the self-heal is complete writes are blocked. Here is the code: xlators/features/locks/src/inodelk.c - line 225 if (__blocked_lock_conflict (dom, lock) && !(__owner_has_lock (dom, lock))) { ret = -EAGAIN; if (can_block == 0) goto out; gettimeofday (&lock->blkd_time, NULL); list_add_tail (&lock->blocked_locks, &dom->blocked_inodelks); } This leads to hangs in applications. Fix: Since we want to prevent two parallel self-heals. We let them compete in a separate "domain". Lets call the domain on which the locks have been taken on in previous approach as "data-domain". In the new approach When a self-heal is triggered, it acquires a full lock in the new domain "self-heal-domain". After this it performs data-self-heal using the locks in "data-domain" as before. unlock the full file lock in "self-heal-domain" With this approach, application's writevs don't have to wait in pending queue when more than 1 self-heal is triggered. Change-Id: Id79aef3dfa888945977fb9758374ac41c320d0d5 BUG: 967717 Signed-off-by: Pranith Kumar K <pkarampu> Reviewed-on: http://review.gluster.org/5100 Tested-by: Gluster Build System <jenkins.com> Reviewed-by: Vijay Bellur <vbellur>
https://code.engineering.redhat.com/gerrit/#/c/10494/
Pranith can you please provide the test case to verify this bug?
Verified the fix on the build: ============================== glusterfs 3.4.0.31rhs built on Sep 5 2013 08:23:16 Test Case: =========== 1. Create a replicate volume (1 x 2). Start the volume. 2. Create 4 fuse mounts. From all the mount start dd on a file: "dd if=/dev/urandom of=./test_file1 bs=1K count=20480000" 3. While dd in progress, bring down a brick. 4. Bring back brick online while dd is still in progress. 5. Take volume statedump. 6. Check the brick statedumps. Expected result: =============== 1. In statedump search for "self-heal" keyword. In self-heal domain one of the mount process will be having a active lock and all other process will be in blocked state. ++++++++++++++++++++++++++++++++++ Example: ++++++++++++++++++++++++++++++++++ [xlator.features.locks.vol_dis_1_rep_2-locks.inode] path=/testdir_gluster/test_file1 mandatory=0 inodelk-count=3352 lock-dump.domain.domain=vol_dis_1_rep_2-replicate-0:self-heal inodelk.inodelk[0](ACTIVE)=type=WRITE, whence=0, start=0, len=0, pid = 18446744073709551615, owner=400a6058f47f0000, transport=0x1a42860, , granted at Fri Sep 6 11:26:59 2013 inodelk.inodelk[1](BLOCKED)=type=WRITE, whence=0, start=0, len=0, pid = 18446744073709551615, owner=7ca9a2144e7f0000, transport=0x1a488c0, , blocked at Fri Sep 6 11:27:00 2013 inodelk.inodelk[2](BLOCKED)=type=WRITE, whence=0, start=0, len=0, pid = 18446744073709551615, owner=1497d664317f0000, transport=0x1a42600, , blocked at Fri Sep 6 11:27:00 2013 inodelk.inodelk[3](BLOCKED)=type=WRITE, whence=0, start=0, len=0, pid = 18446744073709551615, owner=b027b6b8f97f0000, transport=0x1a02190, , blocked at Fri Sep 6 11:27:00 2013 2. Writes on the file from mount shouldn't hang and should be successfully completed. 3. self-heal should be successful. {check mount, glustershd.log for self-heal completion. Example: ========== [2013-09-06 11:54:08.509665] I [afr-self-heal-common.c:2840:afr_log_self_heal_completion_status] 0-vol_dis_1_rep_2-replicate-0: metadata self heal is successfully com pleted, backgroung data self heal is successfully completed, from vol_dis_1_rep_2-client-0 with 6677982208 6677982208 sizes - Pending matrix: [ [ 0 1239959 ] [ 93 9 3 ] ] on /testdir_gluster/test_file1 Actual result: =============== As expected. Bug is fixed . Moving bug to verified state.
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. http://rhn.redhat.com/errata/RHBA-2013-1262.html