[PATCH] nilfs2: fix sync silent failure

[Ryusuke Konishi]

This is another fix for the silent sync failure related to sb->s_bdi.

The commit 5129a469, which was merged to -rc6, let me know this
problem.  I'm sorry that I was late to realize this.

Nilfs uses an own get_sb callback, and needed to set s_bdi for itself.
I confirmed this patch made ->sync_fs() called as intended.

I hope this is sent for 2.6.34.  Please let me know if you have any
comments.

Thanks,
Ryusuke Konishi
---
From: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxxxxxx>

As of 32a88aa1, __sync_filesystem() will return 0 if s_bdi is not set.
And nilfs does not set s_bdi anywhere.  I noticed this problem by the
warning introduced by the recent commit 5129a469 ("Catch filesystem
lacking s_bdi").

 WARNING: at fs/super.c:959 vfs_kern_mount+0xc5/0x14e()
 Hardware name: PowerEdge 2850
 Modules linked in: nilfs2 loop tpm_tis tpm tpm_bios video shpchp pci_hotplug output dcdbas
 Pid: 3773, comm: mount.nilfs2 Not tainted 2.6.34-rc6-debug #38
 Call Trace:
  [<c1028422>] warn_slowpath_common+0x60/0x90
  [<c102845f>] warn_slowpath_null+0xd/0x10
  [<c1095936>] vfs_kern_mount+0xc5/0x14e
  [<c1095a03>] do_kern_mount+0x32/0xbd
  [<c10a811e>] do_mount+0x671/0x6d0
  [<c1073794>] ? __get_free_pages+0x1f/0x21
  [<c10a684f>] ? copy_mount_options+0x2b/0xe2
  [<c107b634>] ? strndup_user+0x48/0x67
  [<c10a81de>] sys_mount+0x61/0x8f
  [<c100280c>] sysenter_do_call+0x12/0x32

This ensures to set s_bdi for nilfs and fixes the sync silent failure.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxxxxxx>
---
 fs/nilfs2/super.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index 0cdbc5e..48145f5 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -749,6 +749,7 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent,
 	sb->s_export_op = &nilfs_export_ops;
 	sb->s_root = NULL;
 	sb->s_time_gran = 1;
+	sb->s_bdi = nilfs->ns_bdi;
 
 	err = load_nilfs(nilfs, sbi);
 	if (err)
-- 
1.6.3.4
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