Red Hat Bugzilla – Bug 1286092
Duplicate files seen on mount point while trying to create files which are greater than the brick size
Last modified: 2018-01-15 13:16:45 EST
1. Posix_mknod succeeds even though linkto xattr is not set because of no space. However the dentry/file is created. Hence this is a file with only T bit set, but without any linkto xattr.
2. Since mknod succeeds, dht proceeds to create data file on a subvol with enough space (min-free disk scenario).
3. Now we've two files and both are data files (because of lack of linkto xattr on hashed-subvol).
Also, since the file on hashed-subvol has only T bit set, all calls to IS_DHT_MIGRATION_PHASE2 succeed. This results in fops like dht_writev_cbk, dht_stat_cbk etc (fops handling migration) to falsely assume that a migration is going on and invoke dht_migration_complete_check task, which fails because of lack of linkto xattr. This error is propagated back to application in these calls (write, stat etc).
Two possible fixes.
1. make posix_mknod atomic with respect to file creation and xattr setting. It should succeed only if both succeed. When xattr setting fails, it should cleanup the file.
2. dht_linkfile_create_cbk should double check whether the file created is indeed a linkto file (by asking for linkto xattr and iatt in cbk). If it finds that file created is not a linkto file, it'll cleanup the file and fails the create call with appropriate error (ENOSPC in this case).
With patch , this bug will go away. Note that  is already part of 3.4.0 branch