[PATCH 6/7] xfs: fix bad_features2 fixups for the root filesystem

Christoph Hellwig
2009-01-09T22:13:02Z

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Currently the bad_features2 fixup and the alignment updates in the superblock
are skipped if we mount a filesystem read-only. But for the root filesystem
the typical case is to mount read-only first and only later remount writeable
so we'll never perform this update at all. It's not a big problem but means
the logs of people needing the fixup get spammed at every boot because they
never happen on disk.

Reported-by: Arkadiusz Miskiewicz <arekm@maven.pl>
Signed-off-by: Christoph Hellwig <hch@lst.de>

Index: xfs/fs/xfs/xfs_mount.c
===================================================================
--- xfs.orig/fs/xfs/xfs_mount.c 2009-01-02 18:39:11.579671462 +0100
+++ xfs/fs/xfs/xfs_mount.c 2009-01-03 21:42:36.741548942 +0100
@@ -45,7 +45,6 @@
#include "xfs_fsops.h"
#include "xfs_utils.h"

-STATIC int xfs_mount_log_sb(xfs_mount_t *, __int64_t);
STATIC int xfs_uuid_mount(xfs_mount_t *);
STATIC void xfs_unmountfs_wait(xfs_mount_t *);

@@ -682,7 +681,7 @@ xfs_initialize_perag_data(xfs_mount_t *m
* Update alignment values based on mount options and sb values
*/
STATIC int
-xfs_update_alignment(xfs_mount_t *mp, __uint64_t *update_flags)
+xfs_update_alignment(xfs_mount_t *mp)
{
xfs_sb_t *sbp = &(mp->m_sb);

@@ -736,11 +735,11 @@ xfs_update_alignment(xfs_mount_t *mp, __
if (xfs_sb_version_hasdalign(sbp)) {
if (sbp->sb_unit != mp->m_dalign) {
sbp->sb_unit = mp->m_dalign;
- *update_flags |= XFS_SB_UNIT;
+ mp->m_update_flags |= XFS_SB_UNIT;
}
if (sbp->sb_width != mp->m_swidth) {
sbp->sb_width = mp->m_swidth;
- *update_flags |= XFS_SB_WIDTH;
+ mp->m_update_flags |= XFS_SB_WIDTH;
}
}
} else if ((mp->m_flags & XFS_MOUNT_NOALIGN) != XFS_MOUNT_NOALIGN &&
@@ -905,7 +904,6 @@ xfs_mountfs(
xfs_sb_t *sbp = &(mp->m_sb);
xfs_inode_t *rip;
__uint64_t resblks;
- __int64_t update_flags = 0LL;
uint quotamount, quotaflags;
int uuid_mounted = 0;
int error = 0;
@@ -933,7 +931,7 @@ xfs_mountfs(
"XFS: correcting sb_features alignment problem");
sbp->sb_features2 |= sbp->sb_bad_features2;
sbp->sb_bad_features2 = sbp->sb_features2;
- update_flags |= XFS_SB_FEATURES2 | XFS_SB_BAD_FEATURES2;
+ mp->m_update_flags |= XFS_SB_FEATURES2 | XFS_SB_BAD_FEATURES2;

/*
* Re-check for ATTR2 in case it was found in bad_features2
@@ -947,11 +945,11 @@ xfs_mountfs(
if (xfs_sb_version_hasattr2(&mp->m_sb) &&
(mp->m_flags & XFS_MOUNT_NOATTR2)) {
xfs_sb_version_removeattr2(&mp->m_sb);
- update_flags |= XFS_SB_FEATURES2;
+ mp->m_update_flags |= XFS_SB_FEATURES2;

/* update sb_versionnum for the clearing of the morebits */
if (!sbp->sb_features2)
- update_flags |= XFS_SB_VERSIONNUM;
+ mp->m_update_flags |= XFS_SB_VERSIONNUM;
}

/*
@@ -960,7 +958,7 @@ xfs_mountfs(
* allocator alignment is within an ag, therefore ag has
* to be aligned at stripe boundary.
*/
- error = xfs_update_alignment(mp, &update_flags);
+ error = xfs_update_alignment(mp);
if (error)
goto error1;

@@ -1137,10 +1135,12 @@ xfs_mountfs(
}

/*
- * If fs is not mounted readonly, then update the superblock changes.
+ * If this is a read-only mount defer the superblock updates until
+ * the next remount into writeable mode. Otherwise we would never
+ * perform the update e.g. for the root filesystem.
*/
- if (update_flags && !(mp->m_flags & XFS_MOUNT_RDONLY)) {
- error = xfs_mount_log_sb(mp, update_flags);
+ if (mp->m_update_flags && !(mp->m_flags & XFS_MOUNT_RDONLY)) {
+ error = xfs_mount_log_sb(mp, mp->m_update_flags);
if (error) {
cmn_err(CE_WARN, "XFS: failed to write sb changes");
goto error4;
@@ -1820,7 +1820,7 @@ xfs_uuid_mount(
* be altered by the mount options, as well as any potential sb_features2
* fixup. Only the first superblock is updated.
*/
-STATIC int
+int
xfs_mount_log_sb(
xfs_mount_t *mp,
__int64_t fields)
Index: xfs/fs/xfs/xfs_mount.h
===================================================================
--- xfs.orig/fs/xfs/xfs_mount.h 2009-01-01 11:53:17.541576193 +0100
+++ xfs/fs/xfs/xfs_mount.h 2009-01-03 21:38:22.555577508 +0100
@@ -327,6 +327,8 @@ typedef struct xfs_mount {
spinlock_t m_sync_lock; /* work item list lock */
int m_sync_seq; /* sync thread generation no. */
wait_queue_head_t m_wait_single_sync_task;
+ __int64_t m_update_flags; /* sb flags we need to update
+ on the next remount,rw */
} xfs_mount_t;

/*
@@ -514,6 +516,7 @@ extern int xfs_mod_incore_sb_unlocked(xf
int64_t, int);
extern int xfs_mod_incore_sb_batch(xfs_mount_t *, xfs_mod_sb_t *,
uint, int);
+extern int xfs_mount_log_sb(xfs_mount_t *, __int64_t);
extern struct xfs_buf *xfs_getsb(xfs_mount_t *, int);
extern int xfs_readsb(xfs_mount_t *, int);
extern void xfs_freesb(xfs_mount_t *);
Index: xfs/fs/xfs/linux-2.6/xfs_super.c
===================================================================
--- xfs.orig/fs/xfs/linux-2.6/xfs_super.c 2009-01-01 11:53:17.294547000 +0100
+++ xfs/fs/xfs/linux-2.6/xfs_super.c 2009-01-03 21:47:58.367578173 +0100
@@ -1197,6 +1197,7 @@ xfs_fs_remount(
struct xfs_mount *mp = XFS_M(sb);
substring_t args[MAX_OPT_ARGS];
char *p;
+ int error;

while ((p = strsep(&options, ",")) != NULL) {
int token;
@@ -1247,11 +1248,25 @@ xfs_fs_remount(
}
}

- /* rw/ro -> rw */
+ /* ro -> rw */
if ((mp->m_flags & XFS_MOUNT_RDONLY) && !(*flags & MS_RDONLY)) {
mp->m_flags &= ~XFS_MOUNT_RDONLY;
if (mp->m_flags & XFS_MOUNT_BARRIER)
xfs_mountfs_check_barriers(mp);
+
+ /*
+ * If this is the first remount to writeable state we
+ * might have some superblock changes to update.
+ */
+ if (mp->m_update_flags) {
+ error = xfs_mount_log_sb(mp, mp->m_update_flags);
+ if (error) {
+ cmn_err(CE_WARN,
+ "XFS: failed to write sb changes");
+ return error;
+ }
+ mp->m_update_flags = 0;
+ }
}

/* rw -> ro */