2010-12-03 01:26:10

by djwong

[permalink] [raw]
Subject: [PATCH] ext3: Set barrier=0 when block device does not advertise flush support

If the user tries to enable write flushes with "barrier=1" and the underlying
block device does not support flushes, print a message and set barrier=0.

Signed-off-by: Darrick J. Wong <[email protected]>
---

fs/ext3/super.c | 14 ++++++++++++++
1 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/fs/ext3/super.c b/fs/ext3/super.c
index d15209e..75ca265 100644
--- a/fs/ext3/super.c
+++ b/fs/ext3/super.c
@@ -1691,6 +1691,13 @@ static int ext3_fill_super (struct super_block *sb, void *data, int silent)
NULL, 0))
goto failed_mount;

+ /* Catch barrier=1 and no flush support */
+ if (test_opt(sb, BARRIER) &&
+ !(sb->s_bdev->bd_disk->queue->flush_flags & REQ_FLUSH)) {
+ ext3_msg(sb, KERN_WARNING, "flush not supported; disabling.");
+ clear_opt(sbi->s_mount_opt, BARRIER);
+ }
+
sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
(test_opt(sb, POSIX_ACL) ? MS_POSIXACL : 0);

@@ -2574,6 +2581,13 @@ static int ext3_remount (struct super_block * sb, int * flags, char * data)
goto restore_opts;
}

+ /* Catch barrier=1 and no flush support */
+ if (test_opt(sb, BARRIER) &&
+ !(sb->s_bdev->bd_disk->queue->flush_flags & REQ_FLUSH)) {
+ ext3_msg(sb, KERN_WARNING, "flush not supported; disabling.");
+ clear_opt(sbi->s_mount_opt, BARRIER);
+ }
+
if (test_opt(sb, ABORT))
ext3_abort(sb, __func__, "Abort forced by user");