From 376994828fd3753aba75d492859727ca76f6a293 Mon Sep 17 00:00:00 2001 From: Chunwei Chen Date: Fri, 11 Aug 2017 08:57:54 -0700 Subject: [PATCH] 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 Reviewed-by: George Melikov Signed-off-by: Chunwei Chen Closes #6478 Closes #6494 --- module/zfs/zfs_vnops.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/module/zfs/zfs_vnops.c b/module/zfs/zfs_vnops.c index 4658a2051..53c5e4f23 100644 --- a/module/zfs/zfs_vnops.c +++ b/module/zfs/zfs_vnops.c @@ -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); /*