svn commit: r316928 - vendor-sys/illumos/dist/uts/common/fs/zfs

[Andriy Gapon]

Author: avg
Date: Fri Apr 14 18:38:53 2017
New Revision: 316928
URL: https://svnweb.freebsd.org/changeset/base/316928

Log:
  7256 low probability race in zfs_get_data
  
  illumos/illumos-gate at 0c94e1af6784c69a1dea25e0e35dd13b2b91e2e5
  https://github.com/illumos/illumos-gate/commit/0c94e1af6784c69a1dea25e0e35dd13b2b91e2e5
  
  https://www.illumos.org/issues/7256
                           error = dmu_sync(zio, lr->lr_common.lrc_txg,
                                zfs_get_done, zgd);
                           ASSERT(error || lr->lr_length <= zp->z_blksz);
    It's possible, although extremely rare, that the zfs_get_done() callback is
    executed before dmu_sync() returns.
    In that case the znode's range lock is dropped and the znode is unreferenced.
    Thus, the assertion can access some invalid or wrong data via the zp pointer.
    size variable caches the correct value of z_blksz and can be safely used here.
  
  Reviewed by: Matt Ahrens <mahrens at delphix.com>
  Reviewed by: Pavel Zakharov <pavel.zakharov at delphix.com>
  Approved by: Dan McDonald <danmcd at omniti.com>
  Author: Andriy Gapon <andriy.gapon at clusterhq.com>

Modified:
  vendor-sys/illumos/dist/uts/common/fs/zfs/zfs_vnops.c

Modified: vendor-sys/illumos/dist/uts/common/fs/zfs/zfs_vnops.c
==============================================================================
--- vendor-sys/illumos/dist/uts/common/fs/zfs/zfs_vnops.c	Fri Apr 14 18:38:21 2017	(r316927)
+++ vendor-sys/illumos/dist/uts/common/fs/zfs/zfs_vnops.c	Fri Apr 14 18:38:53 2017	(r316928)
@@ -1142,7 +1142,7 @@ zfs_get_data(void *arg, lr_write_t *lr, 
 
 			error = dmu_sync(zio, lr->lr_common.lrc_txg,
 			    zfs_get_done, zgd);
-			ASSERT(error || lr->lr_length <= zp->z_blksz);
+			ASSERT(error || lr->lr_length <= size);
 
 			/*
 			 * On success, we need to wait for the write I/O