On 4/29/25 17:48, Christoph Hellwig wrote:
On Tue, Apr 29, 2025 at 02:32:08PM +0530, Nirjhar Roy (IBM) wrote:
Bug: When we compile the kernel with CONFIG_XFS_SUPPORT_V4=y,
remount with "-o remount,noattr2" on a v5 XFS does not
fail explicitly.
Reproduction:
mkfs.xfs -f /dev/loop0
mount /dev/loop0 /mnt/scratch
mount -o remount,noattr2 /dev/loop0 /mnt/scratch
However, with CONFIG_XFS_SUPPORT_V4=n, the remount
correctly fails explicitly. This is because the way the
following 2 functions are defined:
static inline bool xfs_has_attr2 (struct xfs_mount *mp)
{
return !IS_ENABLED(CONFIG_XFS_SUPPORT_V4) ||
(mp->m_features & XFS_FEAT_ATTR2);
}
static inline bool xfs_has_noattr2 (const struct xfs_mount *mp)
{
return mp->m_features & XFS_FEAT_NOATTR2;
}
xfs_has_attr2() returns true when CONFIG_XFS_SUPPORT_V4=n
and hence, the the following if condition in
xfs_fs_validate_params() succeeds and returns -EINVAL:
/*
* We have not read the superblock at this point, so only the attr2
* mount option can set the attr2 feature by this stage.
*/
if (xfs_has_attr2(mp) && xfs_has_noattr2(mp)) {
xfs_warn(mp, "attr2 and noattr2 cannot both be specified.");
return -EINVAL;
}
With CONFIG_XFS_SUPPORT_V4=y, xfs_has_attr2() always return
false and hence no error is returned.
Fix: Check if the existing mount has crc enabled(i.e, of
type v5 and has attr2 enabled) and the
remount has noattr2, if yes, return -EINVAL.
I have tested xfs/{189,539} in fstests with v4
and v5 XFS with both CONFIG_XFS_SUPPORT_V4=y/n and
they both behave as expected.
This patch also fixes remount from noattr2 -> attr2 (on a v4 xfs).
Related discussion in [1]
[1] https://lore.kernel.org/all/Z65o6nWxT00MaUrW@xxxxxxxxxxxxxxxxxxx/
Signed-off-by: Nirjhar Roy (IBM) <nirjhar.roy.lists@xxxxxxxxx>
---
fs/xfs/xfs_super.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index b2dd0c0bf509..1fd45567ae00 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -2114,6 +2114,22 @@ xfs_fs_reconfigure(
if (error)
return error;
+ /* attr2 -> noattr2 */
+ if (xfs_has_noattr2(new_mp)) {
+ if (xfs_has_crc(mp)) {
+ xfs_warn(mp, "attr2 and noattr2 cannot both be specified.");
Nit: normal xfs style is to move the message to a new line when іt
overflows 80 characters:
if (xfs_has_crc(mp)) {
xfs_warn(mp,
"attr2 and noattr2 cannot both be specified.");
+ return -EINVAL;
+ }
+ else {
No need for an else after a return. And for cases where there is an
else the kernel coding style keeps it on the same line as the closing
brace.
+ /* Now that mp has been modified according to the remount options, we do a
+ * final option validation with xfs_finish_flags() just like it is done
+ * during mount. We cannot use xfs_finish_flags() on new_mp as it contains
+ * only the user given options.
+ */
Please keep comments to 80 characters. Also the kernel coding style
keeps the
/*
at the beginning of a comment on a separate line.
Sure, I will address the above coding style related issues. Thank you.
--NR
--
Nirjhar Roy
Linux Kernel Developer
IBM, Bangalore
