On 2017年09月23日 08:48, Liu Bo wrote:
On Sat, Sep 23, 2017 at 08:46:55AM +0800, Qu Wenruo wrote:
On 2017年09月23日 07:36, Liu Bo wrote:
This uses a bool 'do_backup' to help understand this piece of code.
Signed-off-by: Liu Bo <bo.li.liu@xxxxxxxxxx>
---
This is based on a patch "Btrfs: do not backup tree roots when fsync".
fs/btrfs/disk-io.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index cdb7043..9811b9d 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3691,6 +3691,7 @@ int write_all_supers(struct btrfs_fs_info *fs_info, int max_mirrors)
int max_errors;
int total_errors = 0;
u64 flags;
+ bool do_backup = (max_mirrors == 0);
Why not replacing @max_mirrors with @do_backup as parameter?
If I read the code correctly, max_mirrors is not just for deciding
backup.
That's strange.
write_all_supers() only uses @max_mirrors by passing it to
write_dev_supers() and wait_dev_supers().
Both of the write/wait_dev_supers() will replace @max_mirrors to
BTRFS_SUPER_MIRROR_MAX if it's zero.
Further more, all write_all_supers() callers just pass @max_mirrors as
bool (either 0 or 1).
So I don't see any point not replacing the parameter as bool.
Thanks,
Qu
thanks,
-liubo
Thanks,
Qu
do_barriers = !btrfs_test_opt(fs_info, NOBARRIER);
@@ -3699,7 +3700,7 @@ int write_all_supers(struct btrfs_fs_info *fs_info, int max_mirrors)
* not from fsync where the tree roots in fs_info have not
* been consistent on disk.
*/
- if (max_mirrors == 0)
+ if (do_backup)
backup_super_roots(fs_info);
sb = fs_info->super_for_commit;
--
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