similar to: Details about compression and extents

The rule originally comes from nocow writing, but snapshot-aware defrag is a different case, the extent has been writen and we''re not going to change the extent but add a reference on the data. So we''re able to allow such compressed extents to be merged into one bigger extent if they''re pointing to the same data. Signed-off-by: Liu Bo <bo.li.liu@oracle.com> ---

Returns a file''s size on disk. Had been posted by Chris Ball over a year ago (http://article.gmane.org/gmane.comp.file-systems.btrfs/2873). Chris Mason suggested a couple of improvements back then, which I have implemented in this version: - use u64 to return the result - replaced the loop while (1) { struct btrfs_ordered_extent *ordered;

I created a btrfs file system with a single 420 megabyte file in it. And, when I look at the file system with btrfs-debug, I see gigantic extents, as large as 99 megabytes: > $ sudo btrfs-debug-tree /dev/sdb | grep extent > ... > dev extent chunk_tree 3 > dev extent chunk_tree 3 > extent data disk byte 80084992 nr 99958784 > extent data

Provide for modification of the limit of compressed extent size utilizing mount-time configuration settings. The size of compressed extents was limited to 128K, which leads to fragmentation of the extents (although the extents themselves may still be located contiguously). This limit is put in place to ease the RAM required when spreading compression across several CPUs, and to make sure the

I noticed that btrfs fi defrag -c<method> can''t be used to compress files unless they are fragmented. This patch corrects the problem, by informing should_defrag_range if compression is enabled, and skipping tests for extent and adjacent extents if it is. Andrew Mahone (1): btrfs: ignore unfragmented file checks in defrag when compression enabled fs/btrfs/ioctl.c | 10

In btrfs if we mount with "compress" we have no way to disable compressing by remounting (mount -o remount /mnt/btrfs), only by unmounting and mounting without "compress". This patch adds "nocompress" mount option which can be used to remount the filesystem without compression: # mount -o remount,nocompress /mnt/btrfs This option is usefull in cases when we have a

I''ve noticed that: - with x86-64 Fedora 15 DVD install images: - du -sh <ROOT VOLUME> was 36 GB - btrfs df | grep -i data have shown over 40 GB used - without - du -sh <ROOT VOLUME> is 34 GB - btrfs df | grep -i data have shown less then 34 GB used It seems that iso files are considered compressable while they may not be (and penalty is severe - 3x). Regards

I noticed a few days ago that btrfs fi defrag -cXXX can not be used to compress files unless they are fragmented. The attached patch passes the compression flag to should_defrag_range, where it disables the adjacent-extent and extent size checks if set. The inline/sparse extent check is not modified - I assumed it would not be useful to compress inline extents. -- Andrew Mahone andrew DOT mahone

As I''ve been using btrfs with an external USB drive, I wonder how to handle efficiently the compression setting. When I plug a drive in to ubuntu, it is automatically mounted. Its mounted without the compression option as its not in fstab. I don''t see it as desirable to install each usb drive in fstab on each computer that it may be used just so that compression is

Hello, is it possible to set nodatacow on a per-file basis? I couldn''t find anything. If not, wouldn''t that be a great feature to get around the performance issues with VM and database storage? Of course cloning should still cause COW. Thanks, Ralf-Peter -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to

Hello folks, I reported a bug here: https://bugzilla.kernel.org/show_bug.cgi?id=63071 but I am not sure if that was the right thing to do. This is producing OOM issues and leading to system crashes (including eventual panics) with such alarming frequency that I wonder if perhaps there is something different about my setup than others. In a nutshell, I originally made the mistake of storing a

Hi, so here it is, LZ4 compression method inside btrfs. The patchset is based on top of current Chris'' for-linus + Andi''s snappy implementation + the fixes from Li Zefan. Passes xfstests and stresstests. I haven''t measured performance on wide range of hardware or workloads, rather wanted to publish the patches before I get distracted again. I''d like to ask

Use access_extent_buffer_page() to point at btree location of inline compressed data so it can be inflated without a memcopy. Signed-off-by: jim owens <jowens@hp.com> Signed-off-by: jim owens <jim6336@gmail.com> --- V2 fixes whitespace checkpatch warning fs/btrfs/extent_io.c | 16 ++++++++++++++++ fs/btrfs/extent_io.h | 3 +++ 2 files changed, 19 insertions(+), 0 deletions(-)

I noticed a huge problem with the free space cache that was presenting as an early ENOSPC. Turns out when writing the free space cache out I forgot to take into account pinned extents and more importantly clusters. This would result in us leaking free space everytime we unmounted the filesystem and remounted it. I fix this by making sure to check and see if the current block group has a cluster

I''ve been working to try to improve the write-ahead log''s performance, and I found that the bottleneck addresses in the checksum items, especially when we want to make a random write on a large file, e.g a 4G file. Then a idea for this suggested by Chris is to use sub transaction ids and just to log the part of inode that had changed since either the last log commit or the last

From: Anand <anand.jain@oracle.com> This patch adds creation-time to the snapshot list display, which would help user to better manage the snapshots when number of snapshots grow substantially. This patch is developed and on top of the send/receive btrfs and btrfs-progs repo at git://github.com/ablock84/linux-btrfs.git (send-v2) git://github.com/ablock84/btrfs-progs.git (send-v2)

Hi, For a medium term project, I''m thinking of working on transparent compression for Btrfs. Please give any hints and comments on how we would want to go about this, the features we would like to have and some common pitfalls to avoid. Is looking at how it''s done in Reiser4, a good idea ? Can we allow the compression algorithm be configurable on a per file basis, may be

Just a quick update, I''ve dropped the hashing stuff in favor of doing a memcmp in the kernel to make sure the data is still the same. The thing that takes a while is reading the data up from disk, so doing a memcmp of the entire buffer isn''t that big of a deal, not to mention there''s a possiblity for malicious users if there is a problem with the hashing algorithms we

We''re going to use this flag EXTENT_DEFRAG to indicate which range belongs to defragment so that we can implement snapshow-aware defrag: We set the EXTENT_DEFRAG flag when dirtying the extents that need defragmented, so later on writeback thread can differentiate between normal writeback and writeback started by defragmentation. This patch is used for the latter one. Originally patch

While exploring some btrfs maintenance with respect to defragmenting I ran the following commands: # filefrag /path/to/34G.file /path/to/5.7G.file /path/to/34G.file: 2406 extents found /path/to/5.7G.file: 572 extents found Thinking those mostly static files could be less fragmented I ran: # btrfs filesystem defragment -c /path/to/34G.file # btrfs filesystem defragment -c /path/to/5.7G.file and