From 1b1f871ca41b08671ebb327dba464aeb6c82e776 Mon Sep 17 00:00:00 2001 From: Susant Palai Date: Tue, 25 Apr 2017 18:32:45 +0530 Subject: cluster/dht: fix on demand migration files from client On demand migration of files i.e. migration done by clients triggered by a setfattr was broken. Dependency on defrag led to crash when migration was triggered from client. Note: This functionality is not available for tiered volumes. Migration from tier served client will fail with ENOTSUP. usage (But refer to the steps mentioned below to avoid any issues) : setfattr -n "trusted.distribute.migrate-data" -v "1" The purpose of fixing the on-demand client migration was to give a workaround where the user has lots of empty directories compared to files and want to do a remove-brick process. Here are the steps to trigger file migration for remove-brick process from client. (This is highly recommended to follow below steps as is) Let's say it is a replica volume and user want to remove a replica pair named brick1 and brick2. (Make sure healing is completed before you run these steps) Step-1: Start remove-brick process - gluster v remove-brick brick1 brick2 start Step-2: Kill the rebalance daemon - ps aux | grep glusterfs | grep rebalance\/ | awk '{print $2}' | xargs kill Step-3: Do a fresh mount as mentioned here - glusterfs -s ${localhostname} --volfile-id rebalance/$volume-name /tmp/mount/point Step-4: Go to one of the bricks (among brick1 and brick2) - cd Step-5: Run the following command. - find . -not \( -path ./.glusterfs -prune \) -type f -not -perm 01000 -exec bash -c 'setfattr -n "distribute.fix.layout" -v "1" ${mountpoint}/$(dirname '{}')' \; -exec setfattr -n "trusted.distribute.migrate-data" -v "1" ${mountpoint}/'{}' \; This command will ignore the linkto files and empty directories. Do a fix-layout of the parent directory. And trigger a migration operation on the files. Step-6: Once this process is completed do "remove-brick force" - gluster v remove-brick brick1 brick2 force Note: Use the above script only when there are large number of empty directories. Since the script does a crawl on the brick side directly and avoids directories those are empty, the time spent on fixing layout on those directories are eliminated(even if the script does not do fix-layout on empty directories, post remove-brick a fresh layout will be built for the directory, hence not affecting application continuity). Detailing the expectation for hardlink migartion with this patch: Hardlink is migrated only for remove-brick process. It is highly essential to have a new mount(step-3) for the hardlink migration to happen. Why?: setfattr operation is an inode based operation. Since, we are doing setfattr from fuse mount here, inode_path will try to build path from the linked dentries to the inode. For a file without hardlinks the path construction will be correct. But for hardlinks, the inode will have multiple dentries linked. Without fresh mount, inode_path will always get the most recently linked dentry. e.g. if there are three hardlinks named dir1/link1, dir2/link2, dir3/link3, on a client where these hardlinks are looked up, inode_path will always return the path dir3/link3 if dir3/link3 was looked up most recently. Hence, we won't be able to create linkto files for all other hardlinks on destination (read gf_defrag_handle_hardlink for more details on hardlink migration). With a fresh mount, the lookup and setfattr become serialized. e.g. link2 won't be looked up until link1 is looked up and migrated. Hence, inode_path will always have the correct path, in this case link1 dentry is picked up(as this is the most recently looked up inode) and the path is built right. Note: If you run the above script on an existing mount(all entries looked up), hard links may not be migrated, but there should not be any other issue. Please raise a bug, if you find any issue. Tests: Manual Change-Id: I9854cdd4955d9e24494f348fb29ba856ea7ac50a BUG: 1450975 Signed-off-by: Susant Palai Reviewed-on: https://review.gluster.org/17115 NetBSD-regression: NetBSD Build System CentOS-regression: Gluster Build System Smoke: Gluster Build System Reviewed-by: Raghavendra G --- xlators/cluster/dht/src/dht-common.h | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) (limited to 'xlators/cluster/dht/src/dht-common.h') diff --git a/xlators/cluster/dht/src/dht-common.h b/xlators/cluster/dht/src/dht-common.h index f982bf6ac1a..786db020427 100644 --- a/xlators/cluster/dht/src/dht-common.h +++ b/xlators/cluster/dht/src/dht-common.h @@ -542,9 +542,6 @@ struct gf_defrag_info_ { int32_t current_thread_count; pthread_cond_t df_wakeup_thread; - /* Hard link handle requirement */ - synclock_t link_lock; - /* lock migration flag */ gf_boolean_t lock_migration_enabled; @@ -645,6 +642,10 @@ struct dht_conf { gf_boolean_t lock_migration_enabled; gf_lock_t lock; + + /* Hard link handle requirement for migration triggered from client*/ + synclock_t link_lock; + }; typedef struct dht_conf dht_conf_t; -- cgit