[PATCH 02b/11] xfsprogs: avoid dependency on Linux XATTR_SIZE_MAX

Jan Tulak
2015-09-03T10:33:24Z

Currently, we depends on Linux XATTR value for on disk
definitions. Which causes trouble on other platforms and
maybe also if this value was to change.

Fix it by creating a custom definition independent from
those in Linux (although with the same values), so it is OK
with the be16 fields used for holding these attributes.

Signed-off-by: Jan Tulak <jtulak@redhat.com>
---
libxfs/xfs_attr_remote.c | 2 +-
libxfs/xfs_format.h | 10 +++++++++-
2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/libxfs/xfs_attr_remote.c b/libxfs/xfs_attr_remote.c
index 5feaf55..98893e2 100644
--- a/libxfs/xfs_attr_remote.c
+++ b/libxfs/xfs_attr_remote.c
@@ -102,7 +102,7 @@ xfs_attr3_rmt_verify(
if (be32_to_cpu(rmt->rm_bytes) > fsbsize - sizeof(*rmt))
return false;
if (be32_to_cpu(rmt->rm_offset) +
- be32_to_cpu(rmt->rm_bytes) > XATTR_SIZE_MAX)
+ be32_to_cpu(rmt->rm_bytes) > XFS_XATTR_SIZE_MAX)
return false;
if (rmt->rm_owner == 0)
return false;
diff --git a/libxfs/xfs_format.h b/libxfs/xfs_format.h
index bb7cc04..046b20f 100644
--- a/libxfs/xfs_format.h
+++ b/libxfs/xfs_format.h
@@ -60,6 +60,14 @@ struct xfs_ifork;
#define XFS_SB_VERSION_MOREBITSBIT 0x8000

/*
+ * The size of a single extended attribute on disk is limited by
+ * the size of index values within the attribute entries themselves.
+ * These are be16 fields, so we can only support attribute data
+ * sizes up to 2^16 bytes in length.
+ */
+#define XFS_XATTR_SIZE_MAX (1 << 16)
+
+/*
* Supported feature bit list is just all bits in the versionnum field because
* we've used them all up and understand them all. Except, of course, for the
* shared superblock bit, which nobody knows what it does and so is unsupported.
@@ -1483,7 +1491,7 @@ struct xfs_acl {
*/
#define XFS_ACL_MAX_ENTRIES(mp) \
(xfs_sb_version_hascrc(&mp->m_sb) \
- ? (XATTR_SIZE_MAX - sizeof(struct xfs_acl)) / \
+ ? (XFS_XATTR_SIZE_MAX - sizeof(struct xfs_acl)) / \
sizeof(struct xfs_acl_entry) \
: 25)

--
2.4.5