Also,
in theory that break following case:
When fs mounted with compress=no, you can uncompress data by btrfs fi
def -vr <path>, because of "bug" in logic/defaults.
And man page show that btrfs "Currently it’s not possible to select no
compression. See also section EXAMPLES."
I have a two simple patches that can provide a way (one to btrfs-progs
and one to btrfs.ko),
to uncompress data on fs mounted with compress=no, by run btrfs fi def
-vrcnone <path>
But behavior on fs mounted with compress, will be recompress data with
selected by "compress" algo,
because of inode_need_compression() logic.
In theory that also must be fixed.
2017-12-14 16:37 GMT+03:00 Timofey Titovets <nefelim4ag@xxxxxxxxx>:
> Compile tested and "battle" tested
>
> 2017-12-14 16:35 GMT+03:00 Timofey Titovets <nefelim4ag@xxxxxxxxx>:
>> Both, defrag ioctl and autodefrag - call btrfs_defrag_file()
>> for file defragmentation.
>>
>> Kernel target extent size default is 256KiB
>> Btrfs progs by default, use 32MiB.
>>
>> Both bigger then max (not fragmented) compressed extent size 128KiB.
>> That lead to rewrite all compressed data on disk.
>>
>> Fix that and also make should_defrag_range() understood
>> if requested target compression are same as current extent compression type.
>> 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 be5bd81b3669..12d4fa5d6dec 100644
>> --- a/fs/btrfs/ioctl.c
>> +++ b/fs/btrfs/ioctl.c
>> @@ -1008,7 +1008,7 @@ 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;
>> @@ -1043,8 +1043,29 @@ 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.
>> @@ -1342,7 +1363,8 @@ 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
>> --
>> 2.15.1
>>
>
>
>
> --
> Have a nice day,
> Timofey.
--
Have a nice day,
Timofey.
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