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authorGeorge Wilson <[email protected]>2019-03-22 16:09:11 -0400
committerBrian Behlendorf <[email protected]>2019-03-22 13:09:11 -0700
commit2efea7c82c5741a50b476bb1dcbc9a74b8f73ad1 (patch)
treea7f5e66611882cd43d729d23591248a1208ed692
parent060f0226e6396a3c7104fedc8d2af7063a27c1f9 (diff)
ZFS Reads may result in unneccesary calls to zil_commit
ZFS supports O_RSYNC for read operations and when specified will ensure the same level of data integrity that O_DSYNC and O_SYNC provides for writes. O_RSYNC by itself has no effect so it must be combined with either O_DSYNC or O_SYNC. However, many platforms don't support O_RSYNC and have mapped O_SYNC to mean O_RSYNC within ZFS. This is incorrect and causes unnecessary calls to zil_commit. Only platforms which support O_RSYNC should implement the zil_commit functionality in the read code path. Reviewed-by: Matt Ahrens <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: George Wilson <[email protected]> Closes #8523
-rw-r--r--include/spl/sys/vnode.h1
-rw-r--r--lib/libspl/include/sys/file.h1
-rw-r--r--module/zfs/zfs_vnops.c10
3 files changed, 9 insertions, 3 deletions
diff --git a/include/spl/sys/vnode.h b/include/spl/sys/vnode.h
index 2c038a6d2..71278b08c 100644
--- a/include/spl/sys/vnode.h
+++ b/include/spl/sys/vnode.h
@@ -58,7 +58,6 @@
#define FOFFMAX O_LARGEFILE
#define FSYNC O_SYNC
#define FDSYNC O_DSYNC
-#define FRSYNC O_SYNC
#define FEXCL O_EXCL
#define FDIRECT O_DIRECT
#define FAPPEND O_APPEND
diff --git a/lib/libspl/include/sys/file.h b/lib/libspl/include/sys/file.h
index b5d985bda..e0752ac25 100644
--- a/lib/libspl/include/sys/file.h
+++ b/lib/libspl/include/sys/file.h
@@ -40,7 +40,6 @@
#define FOFFMAX O_LARGEFILE
#define FSYNC O_SYNC
#define FDSYNC O_DSYNC
-#define FRSYNC O_RSYNC
#define FEXCL O_EXCL
#define FNODSYNC 0x10000 /* fsync pseudo flag */
diff --git a/module/zfs/zfs_vnops.c b/module/zfs/zfs_vnops.c
index bbc171bd2..c77101485 100644
--- a/module/zfs/zfs_vnops.c
+++ b/module/zfs/zfs_vnops.c
@@ -439,6 +439,7 @@ int
zfs_read(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr)
{
int error = 0;
+ boolean_t frsync = B_FALSE;
znode_t *zp = ITOZ(ip);
zfsvfs_t *zfsvfs = ITOZSB(ip);
@@ -466,12 +467,19 @@ zfs_read(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr)
return (0);
}
+#ifdef FRSYNC
/*
* If we're in FRSYNC mode, sync out this znode before reading it.
* Only do this for non-snapshots.
+ *
+ * Some platforms do not support FRSYNC and instead map it
+ * to FSYNC, which results in unnecessary calls to zil_commit. We
+ * only honor FRSYNC requests on platforms which support it.
*/
+ frsync = !!(ioflag & FRSYNC);
+#endif
if (zfsvfs->z_log &&
- (ioflag & FRSYNC || zfsvfs->z_os->os_sync == ZFS_SYNC_ALWAYS))
+ (frsync || zfsvfs->z_os->os_sync == ZFS_SYNC_ALWAYS))
zil_commit(zfsvfs->z_log, zp->z_id);
/*