From: Dave Chinner <dchinner@xxxxxxxxxx>
The mapping size calculation is done last in __xfs_get_blocks(), but
we are going to need the actual mapping size we will use to map the
direct IO correctly in xfs_map_direct(). Factor out the calculation
for code clarity, and move the call to be the first operation in
mapping the extent to the returned buffer.
Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>
---
fs/xfs/xfs_aops.c | 79 ++++++++++++++++++++++++++++++++-----------------------
1 file changed, 46 insertions(+), 33 deletions(-)
diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
index 489ed20..4a29399 100644
--- a/fs/xfs/xfs_aops.c
+++ b/fs/xfs/xfs_aops.c
@@ -1249,6 +1249,47 @@ xfs_map_direct(
}
}
+
+/*
+ * If this is O_DIRECT or the mpage code calling tell them how large the mapping
+ * is, so that we can avoid repeated get_blocks calls.
+ *
+ * If the mapping spans EOF, then we have to break the mapping up as the mapping
+ * for blocks beyond EOF must be marked new so that sub block regions can be
+ * correctly zeroed. We can't do this for mappings within EOF unless the mapping
+ * was just allocated or is unwritten, otherwise the callers would overwrite
+ * existing data with zeros. Hence we have to split the mapping into a range up
+ * to and including EOF, and a second mapping for beyond EOF.
+ */
+static void
+xfs_map_trim_size(
+ struct inode *inode,
+ sector_t iblock,
+ struct buffer_head *bh_result,
+ struct xfs_bmbt_irec *imap,
+ xfs_off_t offset,
+ ssize_t size)
+{
+ xfs_off_t mapping_size;
+
+ mapping_size = imap->br_startoff + imap->br_blockcount - iblock;
+ mapping_size <<= inode->i_blkbits;
+
+ ASSERT(mapping_size > 0);
+ if (mapping_size > size)
+ mapping_size = size;
+ if (offset < i_size_read(inode) &&
+ offset + mapping_size >= i_size_read(inode)) {
+ /* limit mapping to block that spans EOF */
+ mapping_size = roundup_64(i_size_read(inode) - offset,
+ 1 << inode->i_blkbits);
+ }
+ if (mapping_size > LONG_MAX)
+ mapping_size = LONG_MAX;
+
+ bh_result->b_size = mapping_size;
+}
+
STATIC int
__xfs_get_blocks(
struct inode *inode,
@@ -1347,6 +1388,11 @@ __xfs_get_blocks(
goto out_unlock;
}
+ /* trim mapping down to size requested */
+ if (direct || size > (1 << inode->i_blkbits))
+ xfs_map_trim_size(inode, iblock, bh_result,
+ &imap, offset, size);
+
/*
* For unwritten extents do not report a disk address in the buffered
* read case (treat as if we're reading into a hole).
@@ -1392,39 +1438,6 @@ __xfs_get_blocks(
}
}
- /*
- * If this is O_DIRECT or the mpage code calling tell them how large
- * the mapping is, so that we can avoid repeated get_blocks calls.
- *
- * If the mapping spans EOF, then we have to break the mapping up as the
- * mapping for blocks beyond EOF must be marked new so that sub block
- * regions can be correctly zeroed. We can't do this for mappings within
- * EOF unless the mapping was just allocated or is unwritten, otherwise
- * the callers would overwrite existing data with zeros. Hence we have
- * to split the mapping into a range up to and including EOF, and a
- * second mapping for beyond EOF.
- */
- if (direct || size > (1 << inode->i_blkbits)) {
- xfs_off_t mapping_size;
-
- mapping_size = imap.br_startoff + imap.br_blockcount - iblock;
- mapping_size <<= inode->i_blkbits;
-
- ASSERT(mapping_size > 0);
- if (mapping_size > size)
- mapping_size = size;
- if (offset < i_size_read(inode) &&
- offset + mapping_size >= i_size_read(inode)) {
- /* limit mapping to block that spans EOF */
- mapping_size = roundup_64(i_size_read(inode) - offset,
- 1 << inode->i_blkbits);
- }
- if (mapping_size > LONG_MAX)
- mapping_size = LONG_MAX;
-
- bh_result->b_size = mapping_size;
- }
-
return 0;
out_unlock:
--
2.0.0
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