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authorKotresh HR <khiremat@redhat.com>2018-07-12 04:31:01 -0400
committerKotresh HR <khiremat@redhat.com>2018-07-12 04:33:08 -0400
commitfc8046894e688b0cb6185f6f32cdb6df942bb490 (patch)
tree2cd83463b1419ad2945f3901ad940c4bada0417e
parent970ea7a91946be6a8c941b0ebafd34fdb7ca4f44 (diff)
geo-rep: Fix symlink rename syncing issue
Problem: Geo-rep sometimes fails to sync the rename of symlink if the I/O is as follows 1. touch file1 2. ln -s "./file1" sym_400 3. mv sym_400 renamed_sym_400 4. mkdir sym_400 The file 'renamed_sym_400' failed to sync to slave Cause: Assume there are three distribute subvolume (brick1, brick2, brick3). The changelogs are recorded as follows for above I/O pattern. Note that the MKDIR is recorded on all bricks. 1. brick1: ------- CREATE file1 SYMLINK sym_400 RENAME sym_400 renamed_sym_400 MKDIR sym_400 2. brick2: ------- MKDIR sym_400 3. brick3: ------- MKDIR sym_400 The operations on 'brick1' should be processed sequentially. But since MKDIR is recorded on all the bricks, The brick 'brick2/brick3' processed MKDIR first before 'brick1' causing out of order syncing and created directory sym_400 first. Now 'brick1' processed it's changelog. CREATE file1 -> succeeds SYMLINK sym_400 -> No longer present in master. Ignored RENAME sym_400 renamed_sym_400 While processing RENAME, if source('sym_400') doesn't present, destination('renamed_sym_400') is created. But geo-rep stats the name 'sym_400' to confirm source file's presence. In this race, since source name 'sym_400' is present as directory, it doesn't create destination. Hence RENAME is ignored. Fix: The fix is not rely only on stat of source name during RENAME. It should stat the name and if the name is present, gfid should be same. Only then it can conclude the presence of source. fixes: bz#1600405 Change-Id: I9fbec4f13ca6a182798a7f81b356fe2003aff969 Signed-off-by: Kotresh HR <khiremat@redhat.com>
-rw-r--r--geo-replication/syncdaemon/resource.py11
1 files changed, 9 insertions, 2 deletions
diff --git a/geo-replication/syncdaemon/resource.py b/geo-replication/syncdaemon/resource.py
index 575a6605393..7eeced96caf 100644
--- a/geo-replication/syncdaemon/resource.py
+++ b/geo-replication/syncdaemon/resource.py
@@ -621,8 +621,14 @@ class Server(object):
collect_failure(e, EEXIST)
elif op == 'RENAME':
en = e['entry1']
- st = lstat(entry)
- if isinstance(st, int):
+ # The matching disk gfid check validates two things
+ # 1. Validates name is present, return false otherwise
+ # 2. Validates gfid is same, returns false otherwise
+ # So both validations are necessary to decide src doesn't
+ # exist. We can't rely on only gfid stat as hardlink could
+ # be present and we can't rely only on name as name could
+ # exist with differnt gfid.
+ if not matching_disk_gfid(gfid, entry):
if e['stat'] and not stat.S_ISDIR(e['stat']['mode']):
if stat.S_ISLNK(e['stat']['mode']) and \
e['link'] is not None:
@@ -646,6 +652,7 @@ class Server(object):
[ENOENT, EEXIST], [ESTALE])
collect_failure(e, cmd_ret)
else:
+ st = lstat(entry)
st1 = lstat(en)
if isinstance(st1, int):
rename_with_disk_gfid_confirmation(gfid, entry, en)