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| author | Darrick J. Wong <darrick.wong@oracle.com> | 2019-04-24 19:27:41 +0300 |
|---|---|---|
| committer | Darrick J. Wong <darrick.wong@oracle.com> | 2019-04-30 18:19:13 +0300 |
| commit | 710d707d2fa9cf4c2aa9def129e71e99513466ea (patch) | |
| tree | 2c718b082d98f4fd851f44a00b3c5e6229ec6b38 /fs/xfs/xfs_dquot.c | |
| parent | 1749d1ea89bdf3181328b7d846e609d5a0e53e50 (diff) | |
| download | linux-710d707d2fa9cf4c2aa9def129e71e99513466ea.tar.xz | |
xfs: always rejoin held resources during defer roll
During testing of xfs/141 on a V4 filesystem, I observed some
inconsistent behavior with regards to resources that are held (i.e.
remain locked) across a defer roll. The transaction roll always gives
the defer roll function a new transaction, even if committing the old
transaction fails. However, the defer roll function only rejoins the
held resources if the transaction commit succeedied. This means that
callers of defer roll have to figure out whether the held resources are
attached to the transaction being passed back.
Worse yet, if the defer roll was part of a defer finish call, we have a
third possibility: the defer finish could pass back a dirty transaction
with dirty held resources and an error code.
The only sane way to handle all of these scenarios is to require that
the code that held the resource either cancel the transaction before
unlocking and releasing the resources, or use functions that detach
resources from a transaction properly (e.g. xfs_trans_brelse) if they
need to drop the reference before committing or cancelling the
transaction.
In order to make this so, change the defer roll code to join held
resources to the new transaction unconditionally and fix all the bhold
callers to release the held buffers correctly.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Diffstat (limited to 'fs/xfs/xfs_dquot.c')
| -rw-r--r-- | fs/xfs/xfs_dquot.c | 17 |
1 files changed, 9 insertions, 8 deletions
diff --git a/fs/xfs/xfs_dquot.c b/fs/xfs/xfs_dquot.c index 87e6dd5326d5..a1af984e4913 100644 --- a/fs/xfs/xfs_dquot.c +++ b/fs/xfs/xfs_dquot.c @@ -277,7 +277,8 @@ xfs_dquot_set_prealloc_limits(struct xfs_dquot *dqp) /* * Ensure that the given in-core dquot has a buffer on disk backing it, and - * return the buffer. This is called when the bmapi finds a hole. + * return the buffer locked and held. This is called when the bmapi finds a + * hole. */ STATIC int xfs_dquot_disk_alloc( @@ -355,13 +356,14 @@ xfs_dquot_disk_alloc( * If everything succeeds, the caller of this function is returned a * buffer that is locked and held to the transaction. The caller * is responsible for unlocking any buffer passed back, either - * manually or by committing the transaction. + * manually or by committing the transaction. On error, the buffer is + * released and not passed back. */ xfs_trans_bhold(tp, bp); error = xfs_defer_finish(tpp); - tp = *tpp; if (error) { - xfs_buf_relse(bp); + xfs_trans_bhold_release(*tpp, bp); + xfs_trans_brelse(*tpp, bp); return error; } *bpp = bp; @@ -521,7 +523,6 @@ xfs_qm_dqread_alloc( struct xfs_buf **bpp) { struct xfs_trans *tp; - struct xfs_buf *bp; int error; error = xfs_trans_alloc(mp, &M_RES(mp)->tr_qm_dqalloc, @@ -529,7 +530,7 @@ xfs_qm_dqread_alloc( if (error) goto err; - error = xfs_dquot_disk_alloc(&tp, dqp, &bp); + error = xfs_dquot_disk_alloc(&tp, dqp, bpp); if (error) goto err_cancel; @@ -539,10 +540,10 @@ xfs_qm_dqread_alloc( * Buffer was held to the transaction, so we have to unlock it * manually here because we're not passing it back. */ - xfs_buf_relse(bp); + xfs_buf_relse(*bpp); + *bpp = NULL; goto err; } - *bpp = bp; return 0; err_cancel: |