[PATCH 35/46] xfs: cleanup __xfs_dir3_data_check

Christoph Hellwig
2019-11-07T18:25:46Z

Use an offset as the main means for iteration, and only do pointer
arithmetics to find the data/unused entries.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
fs/xfs/libxfs/xfs_dir2_data.c | 59 ++++++++++++++++++++---------------
1 file changed, 33 insertions(+), 26 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_dir2_data.c b/fs/xfs/libxfs/xfs_dir2_data.c
index 50e3fa092ff9..8c729270f9f1 100644
--- a/fs/xfs/libxfs/xfs_dir2_data.c
+++ b/fs/xfs/libxfs/xfs_dir2_data.c
@@ -23,6 +23,22 @@ static xfs_failaddr_t xfs_dir2_data_freefind_verify(
struct xfs_dir2_data_unused *dup,
struct xfs_dir2_data_free **bf_ent);

+/*
+ * The number of leaf entries is limited by the size of the block and the amount
+ * of space used by the data entries. We don't know how much space is used by
+ * the data entries yet, so just ensure that the count falls somewhere inside
+ * the block right now.
+ */
+static inline unsigned int
+xfs_dir2_data_max_leaf_entries(
+ const struct xfs_dir_ops *ops,
+ struct xfs_da_geometry *geo)
+{
+ return (geo->blksize - sizeof(struct xfs_dir2_block_tail) -
+ ops->data_entry_offset) /
+ sizeof(struct xfs_dir2_leaf_entry);
+}
+
/*
* Check the consistency of the data block.
* The input can also be a block-format directory.
@@ -38,23 +54,20 @@ __xfs_dir3_data_check(
xfs_dir2_block_tail_t *btp=NULL; /* block tail */
int count; /* count of entries found */
xfs_dir2_data_hdr_t *hdr; /* data block header */
- xfs_dir2_data_entry_t *dep; /* data entry */
xfs_dir2_data_free_t *dfp; /* bestfree entry */
- xfs_dir2_data_unused_t *dup; /* unused entry */
- char *endp; /* end of useful data */
+ void *endp; /* end of useful data */
int freeseen; /* mask of bestfrees seen */
xfs_dahash_t hash; /* hash of current name */
int i; /* leaf index */
int lastfree; /* last entry was unused */
xfs_dir2_leaf_entry_t *lep=NULL; /* block leaf entries */
struct xfs_mount *mp = bp->b_mount;
- char *p; /* current data position */
int stale; /* count of stale leaves */
struct xfs_name name;
+ unsigned int offset;
+ unsigned int end;
const struct xfs_dir_ops *ops;
- struct xfs_da_geometry *geo;
-
- geo = mp->m_dir_geo;
+ struct xfs_da_geometry *geo = mp->m_dir_geo;

/*
* We can be passed a null dp here from a verifier, so we need to go the
@@ -71,7 +84,7 @@ __xfs_dir3_data_check(
return __this_address;

hdr = bp->b_addr;
- p = (char *)ops->data_entry_p(hdr);
+ offset = ops->data_entry_offset;

switch (hdr->magic) {
case cpu_to_be32(XFS_DIR3_BLOCK_MAGIC):
@@ -79,15 +92,8 @@ __xfs_dir3_data_check(
btp = xfs_dir2_block_tail_p(geo, hdr);
lep = xfs_dir2_block_leaf_p(btp);

- /*
- * The number of leaf entries is limited by the size of the
- * block and the amount of space used by the data entries.
- * We don't know how much space is used by the data entries yet,
- * so just ensure that the count falls somewhere inside the
- * block right now.
- */
if (be32_to_cpu(btp->count) >=
- ((char *)btp - p) / sizeof(struct xfs_dir2_leaf_entry))
+ xfs_dir2_data_max_leaf_entries(ops, geo))
return __this_address;
break;
case cpu_to_be32(XFS_DIR3_DATA_MAGIC):
@@ -99,6 +105,7 @@ __xfs_dir3_data_check(
endp = xfs_dir3_data_endp(geo, hdr);
if (!endp)
return __this_address;
+ end = endp - bp->b_addr;

/*
* Account for zero bestfree entries.
@@ -128,8 +135,10 @@ __xfs_dir3_data_check(
/*
* Loop over the data/unused entries.
*/
- while (p < endp) {
- dup = (xfs_dir2_data_unused_t *)p;
+ while (offset < end) {
+ struct xfs_dir2_data_unused *dup = bp->b_addr + offset;
+ struct xfs_dir2_data_entry *dep = bp->b_addr + offset;
+
/*
* If it's unused, look for the space in the bestfree table.
* If we find it, account for that, else make sure it
@@ -140,10 +149,10 @@ __xfs_dir3_data_check(

if (lastfree != 0)
return __this_address;
- if (endp < p + be16_to_cpu(dup->length))
+ if (offset + be16_to_cpu(dup->length) > end)
return __this_address;
if (be16_to_cpu(*xfs_dir2_data_unused_tag_p(dup)) !=
- (char *)dup - (char *)hdr)
+ offset)
return __this_address;
fa = xfs_dir2_data_freefind_verify(hdr, bf, dup, &dfp);
if (fa)
@@ -158,7 +167,7 @@ __xfs_dir3_data_check(
be16_to_cpu(bf[2].length))
return __this_address;
}
- p += be16_to_cpu(dup->length);
+ offset += be16_to_cpu(dup->length);
lastfree = 1;
continue;
}
@@ -168,15 +177,13 @@ __xfs_dir3_data_check(
* in the leaf section of the block.
* The linear search is crude but this is DEBUG code.
*/
- dep = (xfs_dir2_data_entry_t *)p;
if (dep->namelen == 0)
return __this_address;
if (xfs_dir_ino_validate(mp, be64_to_cpu(dep->inumber)))
return __this_address;
- if (endp < p + ops->data_entsize(dep->namelen))
+ if (offset + ops->data_entsize(dep->namelen) > end)
return __this_address;
- if (be16_to_cpu(*ops->data_entry_tag_p(dep)) !=
- (char *)dep - (char *)hdr)
+ if (be16_to_cpu(*ops->data_entry_tag_p(dep)) != offset)
return __this_address;
if (ops->data_get_ftype(dep) >= XFS_DIR3_FT_MAX)
return __this_address;
@@ -198,7 +205,7 @@ __xfs_dir3_data_check(
if (i >= be32_to_cpu(btp->count))
return __this_address;
}
- p += ops->data_entsize(dep->namelen);
+ offset += ops->data_entsize(dep->namelen);
}
/*
* Need to have seen all the entries and all the bestfree slots.
--
2.20.1