2020-06-16 05:37:46

by Hyunchul Lee

Subject: [PATCH v2] exfat: call sync_filesystem for read-only remount

We need to commit dirty metadata and pages to disk
before remounting exfat as read-only.

This fixes a failure in xfstests generic/452

generic/452 does the following:
cp something <exfat>/
mount -o remount,ro <exfat>

the <exfat>/something is corrupted. because while
exfat is remounted as read-only, exfat doesn't
have a chance to commit metadata and
vfs invalidates page caches in a block device.

Signed-off-by: Hyunchul Lee <[email protected]>
---
Changes from v1:
- Does not check the return value of sync_filesystem to
allow to change from "rw" to "ro" even when this function
fails.
- Add the detailed explanation why generic/452 fails

fs/exfat/super.c | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/fs/exfat/super.c b/fs/exfat/super.c
index e650e65536f8..253a92460d52 100644
--- a/fs/exfat/super.c
+++ b/fs/exfat/super.c
@@ -693,10 +693,20 @@ static void exfat_free(struct fs_context *fc)
}
}

+static int exfat_reconfigure(struct fs_context *fc)
+{
+ fc->sb_flags |= SB_NODIRATIME;
+
+ /* volume flag will be updated in exfat_sync_fs */
+ sync_filesystem(fc->root->d_sb);
+ return 0;
+}
+
static const struct fs_context_operations exfat_context_ops = {
.parse_param = exfat_parse_param,
.get_tree = exfat_get_tree,
.free = exfat_free,
+ .reconfigure = exfat_reconfigure,
};

static int exfat_init_fs_context(struct fs_context *fc)
--
2.17.1

2020-06-17 08:13:18

by Sungjong Seo

Subject: RE: [PATCH v2] exfat: call sync_filesystem for read-only remount

> We need to commit dirty metadata and pages to disk before remounting exfat
> as read-only.
>
> This fixes a failure in xfstests generic/452
>
> generic/452 does the following:
> cp something <exfat>/
> mount -o remount,ro <exfat>
>
> the <exfat>/something is corrupted. because while exfat is remounted as
> read-only, exfat doesn't have a chance to commit metadata and vfs
> invalidates page caches in a block device.
>
> Signed-off-by: Hyunchul Lee <[email protected]>

Acked-by: Sungjong Seo <[email protected]>

> ---
> Changes from v1:
> - Does not check the return value of sync_filesystem to
> allow to change from "rw" to "ro" even when this function
> fails.
> - Add the detailed explanation why generic/452 fails
>
> fs/exfat/super.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/fs/exfat/super.c b/fs/exfat/super.c index
> e650e65536f8..253a92460d52 100644
> --- a/fs/exfat/super.c
> +++ b/fs/exfat/super.c
> @@ -693,10 +693,20 @@ static void exfat_free(struct fs_context *fc)
> }
> }
>
> +static int exfat_reconfigure(struct fs_context *fc) {
> + fc->sb_flags |= SB_NODIRATIME;
> +
> + /* volume flag will be updated in exfat_sync_fs */
> + sync_filesystem(fc->root->d_sb);
> + return 0;
> +}
> +
> static const struct fs_context_operations exfat_context_ops = {
> .parse_param = exfat_parse_param,
> .get_tree = exfat_get_tree,
> .free = exfat_free,
> + .reconfigure = exfat_reconfigure,
> };
>
> static int exfat_init_fs_context(struct fs_context *fc)
> --
> 2.17.1

2020-06-17 08:45:22

by Namjae Jeon

Subject: RE: [PATCH v2] exfat: call sync_filesystem for read-only remount

> > We need to commit dirty metadata and pages to disk before remounting
> > exfat as read-only.
> >
> > This fixes a failure in xfstests generic/452
> >
> > generic/452 does the following:
> > cp something <exfat>/
> > mount -o remount,ro <exfat>
> >
> > the <exfat>/something is corrupted. because while exfat is remounted
> > as read-only, exfat doesn't have a chance to commit metadata and vfs
> > invalidates page caches in a block device.
> >
> > Signed-off-by: Hyunchul Lee <[email protected]>
>
> Acked-by: Sungjong Seo <[email protected]>
Applied. Thanks!