xfs: refactor attr scrub memory allocation function

Move the code that allocates memory buffers for the extended attribute
scrub code into a separate function so we can reduce memory allocations
in the next patch.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>

2 files changed, 26 insertions, 9 deletions

diff --git a/fs/xfs/scrub/attr.c b/fs/xfs/scrub/attr.c
index 13314cf87db8..7cb412ca473c 100644
--- a/fs/xfs/scrub/attr.c
+++ b/fs/xfs/scrub/attr.c
@@ -20,26 +20,41 @@
 #include "scrub/dabtree.h"
 #include "scrub/attr.h"
 
-/* Set us up to scrub an inode's extended attributes. */
+/* Allocate enough memory to hold an attr value and attr block bitmaps. */
 int
-xchk_setup_xattr(
+xchk_setup_xattr_buf(
         struct xfs_scrub        *sc,
-        struct xfs_inode        *ip)
+        size_t                  value_size)
 {
         size_t                  sz;
 
         /*
-         * Allocate the buffer without the inode lock held.  We need enough
-         * space to read every xattr value in the file or enough space to
-         * hold three copies of the xattr free space bitmap.  (Not both at
-         * the same time.)
+         * We need enough space to read an xattr value from the file or enough
+         * space to hold three copies of the xattr free space bitmap.  We don't
+         * need the buffer space for both purposes at the same time.
          */
-        sz = max_t(size_t, XATTR_SIZE_MAX, 3 * sizeof(long) *
-                        BITS_TO_LONGS(sc->mp->m_attr_geo->blksize));
+        sz = 3 * sizeof(long) * BITS_TO_LONGS(sc->mp->m_attr_geo->blksize);
+        sz = max_t(size_t, sz, value_size);
+
         sc->buf = kmem_zalloc_large(sz, KM_SLEEP);
         if (!sc->buf)
                 return -ENOMEM;
 
+        return 0;
+}
+
+/* Set us up to scrub an inode's extended attributes. */
+int
+xchk_setup_xattr(
+        struct xfs_scrub        *sc,
+        struct xfs_inode        *ip)
+{
+        int                     error;
+
+        error = xchk_setup_xattr_buf(sc, XATTR_SIZE_MAX);
+        if (error)
+                return error;
+
         return xchk_setup_inode_contents(sc, ip, 0);
 }
 
diff --git a/fs/xfs/scrub/attr.h b/fs/xfs/scrub/attr.h
index 88bb5e29c60c..27e879aeaafc 100644
--- a/fs/xfs/scrub/attr.h
+++ b/fs/xfs/scrub/attr.h
@@ -62,4 +62,6 @@ xchk_xattr_dstmap(
                         BITS_TO_LONGS(sc->mp->m_attr_geo->blksize);
 }
 
+int xchk_setup_xattr_buf(struct xfs_scrub *sc, size_t value_size);
+
 #endif  /* __XFS_SCRUB_ATTR_H__ */