From: Timofey Titovets <nefelim4ag@xxxxxxxxx>
Both, defrag ioctl and autodefrag - call btrfs_defrag_file()
for file defragmentation.
Kernel default target extent size - 256KiB.
Btrfs progs default - 32MiB.
Both bigger then maximum size of compressed extent - 128KiB.
That lead to rewrite all compressed data on disk.
Fix that by check compression extents with different logic.
As addition, make should_defrag_range() understood compressed extent type,
if requested target compression are same as current extent compression type.
Just don't recompress/rewrite extents.
To avoid useless recompression of compressed extents.
Signed-off-by: Timofey Titovets <nefelim4ag@xxxxxxxxx>
---
fs/btrfs/ioctl.c | 28 +++++++++++++++++++++++++---
1 file changed, 25 insertions(+), 3 deletions(-)
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index a990a9045139..0a5ea1ccc89d 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1142,7 +1142,7 @@ static bool defrag_check_next_extent(struct inode *inode, struct extent_map *em)
static int should_defrag_range(struct inode *inode, u64 start, u32 thresh,
u64 *last_len, u64 *skip, u64 *defrag_end,
- int compress)
+ int compress, int compress_type)
{
struct extent_map *em;
int ret = 1;
@@ -1177,8 +1177,29 @@ static int should_defrag_range(struct inode *inode, u64 start, u32 thresh,
* real extent, don't bother defragging it
*/
if (!compress && (*last_len == 0 || *last_len >= thresh) &&
- (em->len >= thresh || (!next_mergeable && !prev_mergeable)))
+ (em->len >= thresh || (!next_mergeable && !prev_mergeable))) {
ret = 0;
+ goto out;
+ }
+
+
+ /*
+ * Try not recompress compressed extents
+ * thresh >= BTRFS_MAX_UNCOMPRESSED will lead to
+ * recompress all compressed extents
+ */
+ if (em->compress_type != 0 && thresh >= BTRFS_MAX_UNCOMPRESSED) {
+ if (!compress) {
+ if (em->len == BTRFS_MAX_UNCOMPRESSED)
+ ret = 0;
+ } else {
+ if (em->compress_type != compress_type)
+ goto out;
+ if (em->len == BTRFS_MAX_UNCOMPRESSED)
+ ret = 0;
+ }
+ }
+
out:
/*
* last_len ends up being a counter of how many bytes we've defragged.
@@ -1477,7 +1498,8 @@ int btrfs_defrag_file(struct inode *inode, struct file *file,
if (!should_defrag_range(inode, (u64)i << PAGE_SHIFT,
extent_thresh, &last_len, &skip,
- &defrag_end, do_compress)){
+ &defrag_end, do_compress,
+ compress_type)){
unsigned long next;
/*
* the should_defrag function tells us how much to skip
--
2.19.0
