[PATCH] xfs: fix up inode32/64 (re)mount handling

Eric Sandeen
2016-02-17T04:47:53Z

inode32/inode64 allocator behavior with respect to mount,
remount and growfs is a little tricky.

The inode32 mount option should only enable the inode32
allocator heuristics if the filesystem is large enough
for 64-bit inodes to exist. Today, it has this behavior
on the initial mount, but a remount with inode32
unconditionally changes the allocation heuristics, even
for a small fs.

Also, an inode32 mounted small filesystem should transition
to the inode32 allocator if the filesystem is subsequently
grown to a sufficient size. Today that does not happen.

This patch consolidates xfs_set_inode32 and xfs_set_inode64
into a single new function, and moves the "is the maximum inode
number big enough to matter" test into that function, so
it doesn't rely on the caller to get it right - which
remount did not do, previously.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
---

Note, this goes after my token-parsing patch for mount.

diff --git a/fs/xfs/xfs_mount.c b/fs/xfs/xfs_mount.c
index f8c4a50..83c2f92 100644
--- a/fs/xfs/xfs_mount.c
+++ b/fs/xfs/xfs_mount.c
@@ -185,9 +185,6 @@ xfs_initialize_perag(
xfs_agnumber_t index;
xfs_agnumber_t first_initialised = 0;
xfs_perag_t *pag;
- xfs_agino_t agino;
- xfs_ino_t ino;
- xfs_sb_t *sbp = &mp->m_sb;
int error = -ENOMEM;

/*
@@ -230,22 +227,7 @@ xfs_initialize_perag(
radix_tree_preload_end();
}

- /*
- * If we mount with the inode64 option, or no inode overflows
- * the legacy 32-bit address space clear the inode32 option.
- */
- agino = XFS_OFFBNO_TO_AGINO(mp, sbp->sb_agblocks - 1, 0);
- ino = XFS_AGINO_TO_INO(mp, agcount - 1, agino);
-
- if ((mp->m_flags & XFS_MOUNT_SMALL_INUMS) && ino > XFS_MAXINUMBER_32)
- mp->m_flags |= XFS_MOUNT_32BITINODES;
- else
- mp->m_flags &= ~XFS_MOUNT_32BITINODES;
-
- if (mp->m_flags & XFS_MOUNT_32BITINODES)
- index = xfs_set_inode32(mp, agcount);
- else
- index = xfs_set_inode64(mp, agcount);
+ index = xfs_set_inode_alloc(mp, agcount);

if (maxagi)
*maxagi = index;
diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index 2c38bef..40acf8f 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -205,9 +205,8 @@ typedef struct xfs_mount {
#define XFS_MOUNT_GRPID (1ULL << 9) /* group-ID assigned from directory */
#define XFS_MOUNT_NORECOVERY (1ULL << 10) /* no recovery - dirty fs */
#define XFS_MOUNT_DFLT_IOSIZE (1ULL << 12) /* set default i/o size */
-#define XFS_MOUNT_32BITINODES (1ULL << 14) /* do not create inodes above
- * 32 bits in size */
-#define XFS_MOUNT_SMALL_INUMS (1ULL << 15) /* users wants 32bit inodes */
+#define XFS_MOUNT_SMALL_INUMS (1ULL << 14) /* user wants 32bit inodes */
+#define XFS_MOUNT_32BITINODES (1ULL << 15) /* inode32 allocator active */
#define XFS_MOUNT_NOUUID (1ULL << 16) /* ignore uuid during mount */
#define XFS_MOUNT_BARRIER (1ULL << 17)
#define XFS_MOUNT_IKEEP (1ULL << 18) /* keep empty inode clusters*/
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index fe4c14e..044b416 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -577,23 +577,35 @@ xfs_max_file_offset(
}

/*
- * xfs_set_inode32() and xfs_set_inode64() are passed an agcount
- * because in the growfs case, mp->m_sb.sb_agcount is not updated
- * yet to the potentially higher ag count.
+ * Set parameters for inode allocation heuristics, taking into account
+ * filesystem size and inode32/inode64 mount options; i.e. specifically
+ * whether or not XFS_MOUNT_SMALL_INUMS is set.
+ *
+ * Inode allocation patterns are altered only if inode32 is requested
+ * (XFS_MOUNT_SMALL_INUMS), and the filesystem is sufficiently large.
+ * If altered, XFS_MOUNT_32BITINODES is set as well.
+ *
+ * An agcount independent of that in the mount structure is provided
+ * because in the growfs case, mp->m_sb.sb_agcount is not yet updated
+ * to the potentially higher ag count.
+ *
+ * Returns the maximum AG index which may contain inodes.
*/
xfs_agnumber_t
-xfs_set_inode32(struct xfs_mount *mp, xfs_agnumber_t agcount)
+xfs_set_inode_alloc(
+ struct xfs_mount *mp,
+ xfs_agnumber_t agcount)
{
- xfs_agnumber_t index = 0;
+ xfs_agnumber_t index;
xfs_agnumber_t maxagi = 0;
xfs_sb_t *sbp = &mp->m_sb;
xfs_agnumber_t max_metadata;
xfs_agino_t agino;
xfs_ino_t ino;
- xfs_perag_t *pag;

- /* Calculate how much should be reserved for inodes to meet
- * the max inode percentage.
+ /*
+ * Calculate how much should be reserved for inodes to meet
+ * the max inode percentage. Used only for inode32.
*/
if (mp->m_maxicount) {
__uint64_t icount;
@@ -607,54 +619,48 @@ xfs_set_inode32(struct xfs_mount *mp, xfs_agnumber_t agcount)
max_metadata = agcount;
}

+ /* Get the last possible inode in the filesystem */
agino = XFS_OFFBNO_TO_AGINO(mp, sbp->sb_agblocks - 1, 0);
+ ino = XFS_AGINO_TO_INO(mp, agcount - 1, agino);
+
+ /*
+ * If user asked for no more than 32-bit inodes, and the fs is
+ * sufficiently large, set XFS_MOUNT_32BITINODES if we must alter
+ * the allocator to accommodate the request.
+ */
+ if ((mp->m_flags & XFS_MOUNT_SMALL_INUMS) && ino > XFS_MAXINUMBER_32)
+ mp->m_flags |= XFS_MOUNT_32BITINODES;
+ else
+ mp->m_flags &= ~XFS_MOUNT_32BITINODES;

for (index = 0; index < agcount; index++) {
- ino = XFS_AGINO_TO_INO(mp, index, agino);
+ struct xfs_perag *pag;

- if (ino > XFS_MAXINUMBER_32) {
- pag = xfs_perag_get(mp, index);
- pag->pagi_inodeok = 0;
- pag->pagf_metadata = 0;
- xfs_perag_put(pag);
- continue;
- }
+ ino = XFS_AGINO_TO_INO(mp, index, agino);

pag = xfs_perag_get(mp, index);
- pag->pagi_inodeok = 1;
- maxagi++;
- if (index < max_metadata)
- pag->pagf_metadata = 1;
- xfs_perag_put(pag);
- }
- mp->m_flags |= (XFS_MOUNT_32BITINODES |
- XFS_MOUNT_SMALL_INUMS);

- return maxagi;
-}
-
-xfs_agnumber_t
-xfs_set_inode64(struct xfs_mount *mp, xfs_agnumber_t agcount)
-{
- xfs_agnumber_t index = 0;
-
- for (index = 0; index < agcount; index++) {
- struct xfs_perag *pag;
+ if (mp->m_flags & XFS_MOUNT_32BITINODES) {
+ if (ino > XFS_MAXINUMBER_32) {
+ pag->pagi_inodeok = 0;
+ pag->pagf_metadata = 0;
+ } else {
+ pag->pagi_inodeok = 1;
+ maxagi++;
+ if (index < max_metadata)
+ pag->pagf_metadata = 1;
+ else
+ pag->pagf_metadata = 0;
+ }
+ } else {
+ pag->pagi_inodeok = 1;
+ pag->pagf_metadata = 0;
+ }

- pag = xfs_perag_get(mp, index);
- pag->pagi_inodeok = 1;
- pag->pagf_metadata = 0;
xfs_perag_put(pag);
}

- /* There is no need for lock protection on m_flags,
- * the rw_semaphore of the VFS superblock is locked
- * during mount/umount/remount operations, so this is
- * enough to avoid concurency on the m_flags field
- */
- mp->m_flags &= ~(XFS_MOUNT_32BITINODES |
- XFS_MOUNT_SMALL_INUMS);
- return index;
+ return (mp->m_flags & XFS_MOUNT_32BITINODES) ? maxagi : agcount;
}

STATIC int
@@ -1224,10 +1230,12 @@ xfs_fs_remount(
mp->m_flags &= ~XFS_MOUNT_BARRIER;
break;
case Opt_inode64:
- mp->m_maxagi = xfs_set_inode64(mp, sbp->sb_agcount);
+ mp->m_flags &= ~XFS_MOUNT_SMALL_INUMS;
+ mp->m_maxagi = xfs_set_inode_alloc(mp, sbp->sb_agcount);
break;
case Opt_inode32:
- mp->m_maxagi = xfs_set_inode32(mp, sbp->sb_agcount);
+ mp->m_flags |= XFS_MOUNT_SMALL_INUMS;
+ mp->m_maxagi = xfs_set_inode_alloc(mp, sbp->sb_agcount);
break;
default:
/*
diff --git a/fs/xfs/xfs_super.h b/fs/xfs/xfs_super.h
index 499058f..2dfb1ce 100644
--- a/fs/xfs/xfs_super.h
+++ b/fs/xfs/xfs_super.h
@@ -65,8 +65,8 @@ extern __uint64_t xfs_max_file_offset(unsigned int);

extern void xfs_flush_inodes(struct xfs_mount *mp);
extern void xfs_blkdev_issue_flush(struct xfs_buftarg *);
-extern xfs_agnumber_t xfs_set_inode32(struct xfs_mount *, xfs_agnumber_t agcount);
-extern xfs_agnumber_t xfs_set_inode64(struct xfs_mount *, xfs_agnumber_t agcount);
+extern xfs_agnumber_t xfs_set_inode_alloc(struct xfs_mount *,
+ xfs_agnumber_t agcount);

extern const struct export_operations xfs_export_operations;
extern const struct xattr_handler *xfs_xattr_handlers[];