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Subject[PATCH 152/173] ext4: fix credits computing for indirect mapped files
2.6.27.59-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Yongqiang Yang <xiaoqiangnk@gmail.com>

commit 5b41395fcc0265fc9f193aef9df39ce49d64677c upstream.

When writing a contiguous set of blocks, two indirect blocks could be
needed depending on how the blocks are aligned, so we need to increase
the number of credits needed by one.

[ Also fixed a another bug which could further underestimate the
number of journal credits needed by 1; the code was using integer
division instead of DIV_ROUND_UP() -- tytso]

Signed-off-by: Yongqiang Yang <xiaoqiangnk@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
fs/ext4/inode.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5458,13 +5458,12 @@ static int ext4_indirect_trans_blocks(st
/* if nrblocks are contiguous */
if (chunk) {
/*
- * With N contiguous data blocks, it need at most
- * N/EXT4_ADDR_PER_BLOCK(inode->i_sb) indirect blocks
- * 2 dindirect blocks
- * 1 tindirect block
+ * With N contiguous data blocks, we need at most
+ * N/EXT4_ADDR_PER_BLOCK(inode->i_sb) + 1 indirect blocks,
+ * 2 dindirect blocks, and 1 tindirect block
*/
- indirects = nrblocks / EXT4_ADDR_PER_BLOCK(inode->i_sb);
- return indirects + 3;
+ return DIV_ROUND_UP(nrblocks,
+ EXT4_ADDR_PER_BLOCK(inode->i_sb)) + 4;
}
/*
* if nrblocks are not contiguous, worse case, each block touch



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