Fix NULL pointer when O_SYNC read in snapshot

When doing read on a file open with O_SYNC, it will trigger zil_commit.
However for snapshot, there's no zil, so we shouldn't be doing that.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Chunwei Chen <david.chen@osnexus.com>
Closes #6478 
Closes #6494
This commit is contained in:
Chunwei Chen 2017-08-11 08:57:54 -07:00 committed by Brian Behlendorf
parent 761b8ec6bf
commit 376994828f

View File

@ -482,8 +482,10 @@ zfs_read(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr)
/*
* If we're in FRSYNC mode, sync out this znode before reading it.
* Only do this for non-snapshots.
*/
if (ioflag & FRSYNC || zfsvfs->z_os->os_sync == ZFS_SYNC_ALWAYS)
if (zfsvfs->z_log &&
(ioflag & FRSYNC || zfsvfs->z_os->os_sync == ZFS_SYNC_ALWAYS))
zil_commit(zfsvfs->z_log, zp->z_id);
/*