[PATCH 14/22] xfs: shortform directory offsets change for dir3 format

Dave Chinner
2013-04-03T05:12:03Z

From: Dave Chinner <dchinner@redhat.com>

Because the header size for the CRC enabled directory blocks is
larger, the offset of the first entry into a directory block is
different to the dir2 format. The shortform directory stores the
dirent's offset so that it doesn't change when moving from shortform
to block form and back again, and hence it needs to take into
account the different header sizes to maintain the correct offsets.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
fs/xfs/xfs_dir2_format.h | 25 ++++++++++++++-----------
fs/xfs/xfs_dir2_sf.c | 10 +++++-----
2 files changed, 19 insertions(+), 16 deletions(-)

diff --git a/fs/xfs/xfs_dir2_format.h b/fs/xfs/xfs_dir2_format.h
index 7b986d3..a3b1bd8 100644
--- a/fs/xfs/xfs_dir2_format.h
+++ b/fs/xfs/xfs_dir2_format.h
@@ -228,16 +228,6 @@ xfs_dir2_sf_nextentry(struct xfs_dir2_sf_hdr *hdr,
xfs_dir2_byte_to_db(mp, XFS_DIR2_DATA_OFFSET)

/*
- * Offsets of . and .. in data space (always block 0)
- */
-#define XFS_DIR2_DATA_DOT_OFFSET \
- ((xfs_dir2_data_aoff_t)sizeof(struct xfs_dir2_data_hdr))
-#define XFS_DIR2_DATA_DOTDOT_OFFSET \
- (XFS_DIR2_DATA_DOT_OFFSET + xfs_dir2_data_entsize(1))
-#define XFS_DIR2_DATA_FIRST_OFFSET \
- (XFS_DIR2_DATA_DOTDOT_OFFSET + xfs_dir2_data_entsize(2))
-
-/*
* Describe a free area in the data block.
*
* The freespace will be formatted as a xfs_dir2_data_unused_t.
@@ -378,7 +368,20 @@ xfs_dir3_data_unused_p(struct xfs_dir2_data_hdr *hdr)

/*
* Offsets of . and .. in data space (always block 0)
- */
+ *
+ * The macros are used for shortform directories as they have no headers to read
+ * the magic number out of. Shortform directories need to know the size of the
+ * data block header because the sfe embeds the block offset of the entry into
+ * it so that it doesn't change when format conversion occurs. Bad Things Happen
+ * if we don't follow this rule.
+ */
+#define XFS_DIR3_DATA_DOT_OFFSET(mp) \
+ xfs_dir3_data_hdr_size(xfs_sb_version_hascrc(&(mp)->m_sb))
+#define XFS_DIR3_DATA_DOTDOT_OFFSET(mp) \
+ (XFS_DIR3_DATA_DOT_OFFSET(mp) + xfs_dir2_data_entsize(1))
+#define XFS_DIR3_DATA_FIRST_OFFSET(mp) \
+ (XFS_DIR3_DATA_DOTDOT_OFFSET(mp) + xfs_dir2_data_entsize(2))
+
static inline xfs_dir2_data_aoff_t
xfs_dir3_data_dot_offset(struct xfs_dir2_data_hdr *hdr)
{
diff --git a/fs/xfs/xfs_dir2_sf.c b/fs/xfs/xfs_dir2_sf.c
index b975622..6157424 100644
--- a/fs/xfs/xfs_dir2_sf.c
+++ b/fs/xfs/xfs_dir2_sf.c
@@ -535,7 +535,7 @@ xfs_dir2_sf_addname_hard(
* to insert the new entry.
* If it's going to end up at the end then oldsfep will point there.
*/
- for (offset = XFS_DIR2_DATA_FIRST_OFFSET,
+ for (offset = XFS_DIR3_DATA_FIRST_OFFSET(dp->i_mount),
oldsfep = xfs_dir2_sf_firstentry(oldsfp),
add_datasize = xfs_dir2_data_entsize(args->namelen),
eof = (char *)oldsfep == &buf[old_isize];
@@ -617,7 +617,7 @@ xfs_dir2_sf_addname_pick(

sfp = (xfs_dir2_sf_hdr_t *)dp->i_df.if_u1.if_data;
size = xfs_dir2_data_entsize(args->namelen);
- offset = XFS_DIR2_DATA_FIRST_OFFSET;
+ offset = XFS_DIR3_DATA_FIRST_OFFSET(mp);
sfep = xfs_dir2_sf_firstentry(sfp);
holefit = 0;
/*
@@ -688,7 +688,7 @@ xfs_dir2_sf_check(
dp = args->dp;

sfp = (xfs_dir2_sf_hdr_t *)dp->i_df.if_u1.if_data;
- offset = XFS_DIR2_DATA_FIRST_OFFSET;
+ offset = XFS_DIR3_DATA_FIRST_OFFSET(dp->i_mount);
ino = xfs_dir2_sf_get_parent_ino(sfp);
i8count = ino > XFS_DIR2_MAX_SHORT_INUM;

@@ -812,9 +812,9 @@ xfs_dir2_sf_getdents(
* mp->m_dirdatablk.
*/
dot_offset = xfs_dir2_db_off_to_dataptr(mp, mp->m_dirdatablk,
- XFS_DIR2_DATA_DOT_OFFSET);
+ XFS_DIR3_DATA_DOT_OFFSET(mp));
dotdot_offset = xfs_dir2_db_off_to_dataptr(mp, mp->m_dirdatablk,
- XFS_DIR2_DATA_DOTDOT_OFFSET);
+ XFS_DIR3_DATA_DOTDOT_OFFSET(mp));

/*
* Put . entry unless we're starting past it.
--
1.7.10.4