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| author | Jeff Layton <jlayton@kernel.org> | 2019-08-02 13:15:39 -0400 |
|---|---|---|
| committer | Ilya Dryomov <idryomov@gmail.com> | 2019-09-16 12:06:25 +0200 |
| commit | 321fe13c939876b55fbb7780a243c86e577a2151 (patch) | |
| tree | 9963961399b7648c1207012d31b1dc51f50a389c /fs/ceph/super.h | |
| parent | 4766815b1179dbe4fe263a5f95795710e29276e2 (diff) | |
| download | linux-321fe13c939876b55fbb7780a243c86e577a2151.tar.bz2 | |
ceph: add buffered/direct exclusionary locking for reads and writes
xfstest generic/451 intermittently fails. The test does O_DIRECT writes
to a file, and then reads back the result using buffered I/O, while
running a separate set of tasks that are also doing buffered reads.
The client will invalidate the cache prior to a direct write, but it's
easy for one of the other readers' replies to race in and reinstantiate
the invalidated range with stale data.
To fix this, we must to serialize direct I/O writes and buffered reads.
We could just sprinkle in some shared locks on the i_rwsem for reads,
and increase the exclusive footprint on the write side, but that would
cause O_DIRECT writes to end up serialized vs. other direct requests.
Instead, borrow the scheme used by nfs.ko. Buffered writes take the
i_rwsem exclusively, but buffered reads take a shared lock, allowing
them to run in parallel.
O_DIRECT requests also take a shared lock, but we need for them to not
run in parallel with buffered reads. A flag on the ceph_inode_info is
used to indicate whether it's in direct or buffered I/O mode. When a
conflicting request is submitted, it will block until the inode can be
flipped to the necessary mode.
Link: https://tracker.ceph.com/issues/40985
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Diffstat (limited to 'fs/ceph/super.h')
| -rw-r--r-- | fs/ceph/super.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/fs/ceph/super.h b/fs/ceph/super.h index 03e4828c7635..98d7190289c8 100644 --- a/fs/ceph/super.h +++ b/fs/ceph/super.h @@ -513,10 +513,10 @@ static inline struct inode *ceph_find_inode(struct super_block *sb, #define CEPH_I_SEC_INITED (1 << 6) /* security initialized */ #define CEPH_I_CAP_DROPPED (1 << 7) /* caps were forcibly dropped */ #define CEPH_I_KICK_FLUSH (1 << 8) /* kick flushing caps */ -#define CEPH_I_FLUSH_SNAPS (1 << 9) /* need flush snapss */ +#define CEPH_I_FLUSH_SNAPS (1 << 9) /* need flush snapss */ #define CEPH_I_ERROR_WRITE (1 << 10) /* have seen write errors */ #define CEPH_I_ERROR_FILELOCK (1 << 11) /* have seen file lock errors */ - +#define CEPH_I_ODIRECT (1 << 12) /* inode in direct I/O mode */ /* * Masks of ceph inode work. |