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author | Sage Weil <sage@newdream.net> | 2010-03-16 15:28:54 -0700 |
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committer | Sage Weil <sage@newdream.net> | 2010-03-23 07:46:56 -0700 |
commit | 80fc7314a7e26e8d2e4ba5b3d8cc2d4aeb750015 (patch) | |
tree | a8f5c8ee76ac0b566332317388b716e70112088b /fs/ceph/osdmap.c | |
parent | 916623da10e270c7e9e802a7ddfe1ec8f890982d (diff) |
ceph: fix mds sync() race with completing requests
The wait_unsafe_requests() helper dropped the mdsc mutex to wait
for each request to complete, and then examined r_node to get the
next request after retaking the lock. But the request completion
removes the request from the tree, so r_node was always undefined
at this point. Since it's a small race, it usually led to a
valid request, but not always. The result was an occasional
crash in rb_next() while dereferencing node->rb_left.
Fix this by clearing the rb_node when removing the request from
the request tree, and not walking off into the weeds when we
are done waiting for a request. Since the request we waited on
will _always_ be out of the request tree, take a ref on the next
request, in the hopes that it won't be. But if it is, it's ok:
we can start over from the beginning (and traverse over older read
requests again).
Signed-off-by: Sage Weil <sage@newdream.net>
Diffstat (limited to 'fs/ceph/osdmap.c')
0 files changed, 0 insertions, 0 deletions