If an fallocate request fits in EXT_UNINIT_MAX_LEN, then set the
EXT4_GET_BLOCKS_NO_NORMALIZE flag. For larger fallocate requests,
let mballoc.c normalize the request.
This fixes a problem where large requests were being split
into non-contiguous extents due to haldar@xxxxxxxxxx's
"ext4: do not normalize block requests from fallocate."
Testing: Checked that 8.x MB falloc'ed files are still laid down
next to each other (contiguously).
Checked that the maximum size extent (127.9MB) is allocated as 1
extent.
Checked that a 1GB file is somewhat contiguous (often 5-6
non-contiguous extents now).
Checked that a 120MB file can still be falloc'ed even if there are no
single extents large enough to hold it.
Signed-off-by: Greg Harm <gharm@xxxxxxxxxx>
---
fs/ext4/extents.c | 13 ++++++++++---
1 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 57cf568..9819216 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -3761,6 +3761,7 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
int ret2 = 0;
int retries = 0;
struct ext4_map_blocks map;
+ int map_blocks_flags;
unsigned int credits, blkbits = inode->i_blkbits;
/*
@@ -3805,9 +3806,15 @@ retry:
ret = PTR_ERR(handle);
break;
}
- ret = ext4_map_blocks(handle, inode, &map,
- EXT4_GET_BLOCKS_CREATE_UNINIT_EXT |
- EXT4_GET_BLOCKS_NO_NORMALIZE);
+ map_blocks_flags = EXT4_GET_BLOCKS_CREATE_UNINIT_EXT;
+ /*
+ * Don't normalize the request if it can fit in one extent so
+ * that it doesn't get unnecessarily split into multiple
+ * extents.
+ */
+ if (len <= EXT_UNINIT_MAX_LEN << blkbits)
+ map_blocks_flags |= EXT4_GET_BLOCKS_NO_NORMALIZE;
+ ret = ext4_map_blocks(handle, inode, &map, map_blocks_flags);
if (ret <= 0) {
#ifdef EXT4FS_DEBUG
WARN_ON(ret <= 0);
--
1.7.3.1
--
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