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authorYan, Zheng <zheng.z.yan@intel.com>2013-08-12 21:42:15 -0700
committerSage Weil <sage@inktank.com>2013-08-15 11:12:06 -0700
commitb0d7c2231015b331b942746610a05b6ea72977ab (patch)
treea13e3f015fc3144371550b4f5c25363bd66bdf1f /fs/ceph/super.h
parentb150f5c1c759d551da9146435d3dc9df5f7e15ef (diff)
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ceph: introduce i_truncate_mutex
I encountered below deadlock when running fsstress wmtruncate work truncate MDS --------------- ------------------ -------------------------- lock i_mutex <- truncate file lock i_mutex (blocked) <- revoking Fcb (filelock to MIX) send request -> handle request (xlock filelock) At the initial time, there are some dirty pages in the page cache. When the kclient receives the truncate message, it reduces inode size and creates some 'out of i_size' dirty pages. wmtruncate work can't truncate these dirty pages because it's blocked by the i_mutex. Later when the kclient receives the cap message that revokes Fcb caps, It can't flush all dirty pages because writepages() only flushes dirty pages within the inode size. When the MDS handles the 'truncate' request from kclient, it waits for the filelock to become stable. But the filelock is stuck in unstable state because it can't finish revoking kclient's Fcb caps. The truncate pagecache locking has already caused lots of trouble for use. I think it's time simplify it by introducing a new mutex. We use the new mutex to prevent concurrent truncate_inode_pages(). There is no need to worry about race between buffered write and truncate_inode_pages(), because our "get caps" mechanism prevents them from concurrent execution. Reviewed-by: Sage Weil <sage@inktank.com> Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Diffstat (limited to 'fs/ceph/super.h')
-rw-r--r--fs/ceph/super.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index afcd62a6..f1e4e47 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -288,6 +288,7 @@ struct ceph_inode_info {
int i_nr_by_mode[CEPH_FILE_MODE_NUM]; /* open file counts */
+ struct mutex i_truncate_mutex;
u32 i_truncate_seq; /* last truncate to smaller size */
u64 i_truncate_size; /* and the size we last truncated down to */
int i_truncate_pending; /* still need to call vmtruncate */
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