[PATCH 4.9 03/72] xfs: only update mount/resv fields on success in __xfs_ag_resv_init

Greg Kroah-Hartman
2017-04-06T08:41:31Z

From: Christoph Hellwig <hch@lst.de>

commit 4dfa2b84118fd6c95202ae87e62adf5000ccd4d0 upstream.

Try to reserve the blocks first and only then update the fields in
or hanging off the mount structure. This way we can call __xfs_ag_resv_init
again after a previous failure.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
fs/xfs/libxfs/xfs_ag_resv.c | 23 ++++++++++++++---------
1 file changed, 14 insertions(+), 9 deletions(-)

--- a/fs/xfs/libxfs/xfs_ag_resv.c
+++ b/fs/xfs/libxfs/xfs_ag_resv.c
@@ -200,22 +200,27 @@ __xfs_ag_resv_init(
struct xfs_mount *mp = pag->pag_mount;
struct xfs_ag_resv *resv;
int error;
+ xfs_extlen_t reserved;

- resv = xfs_perag_resv(pag, type);
if (used > ask)
ask = used;
- resv->ar_asked = ask;
- resv->ar_reserved = resv->ar_orig_reserved = ask - used;
- mp->m_ag_max_usable -= ask;
+ reserved = ask - used;

- trace_xfs_ag_resv_init(pag, type, ask);
-
- error = xfs_mod_fdblocks(mp, -(int64_t)resv->ar_reserved, true);
- if (error)
+ error = xfs_mod_fdblocks(mp, -(int64_t)reserved, true);
+ if (error) {
trace_xfs_ag_resv_init_error(pag->pag_mount, pag->pag_agno,
error, _RET_IP_);
+ return error;
+ }

- return error;
+ mp->m_ag_max_usable -= ask;
+
+ resv = xfs_perag_resv(pag, type);
+ resv->ar_asked = ask;
+ resv->ar_reserved = resv->ar_orig_reserved = reserved;
+
+ trace_xfs_ag_resv_init(pag, type, ask);
+ return 0;
}

/* Create a per-AG block reservation. */