path: root/xlators/cluster/dht/src/dht-common.c
diff options
authorSusant Palai <>2017-04-25 18:32:45 +0530
committerShyamsundar Ranganathan <>2017-05-30 00:42:58 +0000
commit1b1f871ca41b08671ebb327dba464aeb6c82e776 (patch)
treec03df93f141525db93461c08d48f0ba7511fbaa8 /xlators/cluster/dht/src/dht-common.c
parent0a8b2db2d2c3993b25272a65fecad0d3d2866607 (diff)
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" <filename> 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 <volname> 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 <brick1 path> 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 <volname> 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: NetBSD-regression: NetBSD Build System <> CentOS-regression: Gluster Build System <> Smoke: Gluster Build System <> Reviewed-by: Raghavendra G <>
Diffstat (limited to 'xlators/cluster/dht/src/dht-common.c')
1 files changed, 3 insertions, 0 deletions
diff --git a/xlators/cluster/dht/src/dht-common.c b/xlators/cluster/dht/src/dht-common.c
index 8b4fd5c..c471899 100644
--- a/xlators/cluster/dht/src/dht-common.c
+++ b/xlators/cluster/dht/src/dht-common.c
@@ -4172,6 +4172,9 @@ dht_setxattr (call_frame_t *frame, xlator_t *this,
goto err;
+ if (gf_uuid_is_null (local->loc.pargfid))
+ gf_uuid_copy (local->loc.pargfid, local->loc.parent->gfid);
methods->migration_get_dst_subvol(this, local);
if (!local->rebalance.target_node) {