path: root/rpc/rpc-transport
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authorAmar Tumballi <>2011-09-07 12:53:09 +0530
committerVijay Bellur <>2011-09-12 23:57:38 -0700
commita07bb18c8adeb8597f62095c5d1361c5bad01f09 (patch)
tree55bf7ef630793cfd11fc15e84d859cbfb2184b01 /rpc/rpc-transport
parent09eeaf4e68c225b8e5ccc0a9b4f10f8c4748e205 (diff)
distribute rebalance: handle the open file migration
Complexity involved: To migrate a file with open fd, we have to notify the other client process which has the open fd, and make sure the write()s happening on that fd is properly synced to the migrated file. Once the migration is complete, the client process which has open-fd should get notified and it should start performing all the operations on the new subvolume, instead of earlier cached volume. How to solve the notification part: We can overload the 'postbuf' attribute in the _cbk() function to understand if a file is 'under-migration' or 'migration-complete' state. (This will be something similar to deciding whether a file is DHT-linkfile by its 'mode'). Overall change includes below mentioned major changes: 1. dht_linkfile is decided by only 2 factors (mode(01000), xattr(trusted.glusterfs.dht.linkto)), instead of earlier 3 factors (size==0) 2. in linkfile self-heal part (in 'dht_lookup_everywhere_cbk()'), don't delete a linkfile if there is a open-fd on it. It means, there may be a migration in progress. 3. if a file's revalidate fails with ENOENT, it may be due to file migration, and hence need a lookup_everywhere() 4. There will be 2 phases of file-migration. -> Phase 1: Migration in progress * The source data file will have SGID and STICKY bit set in its mode. * The source data file will have a 'linkto' xattr pointing the destination. * Destination file will have mode set to '01000', and 'linkto' xattr set to itself. -> Phase 2: File migration Complete * The source data file will have mode '01000', and will be 'truncated' to size 0. * The destination file will have inherited mode from the source. (without sgid and sticky bit) and its 'linkto' attribute will be removed. 4. Changes in distribute to work smoothly with a file which is in migration / got migrated. The 'fops' are divided into 3 categories, inode-read, inode-write and others. inode-read fops need to handle only 'phase 2' notification, where as, the inode-write fops need to handle both 'phase 1' and phase2. The inode-write operations will be done on source file, and if any of 'file-migration' procedures are detected in _cbk(), then the operations should be performed on the destination too. when a phase-2 is detected, then the inode-ctx itself should be changed to represent a new layout. With these changes, the open file migration will work smoothly with multiple clients. Change-Id: I512408463814e650f34c62ed009bf2101d016fd6 BUG: 3071 Reviewed-on: Tested-by: Gluster Build System <> Reviewed-by: Vijay Bellur <>
Diffstat (limited to 'rpc/rpc-transport')
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