similar to: State of nocow file attribute

I set the C (NOCOW) and z (Not_Compressed) flags on a folder but the extent counts of files contained there keep increasing. Said files are large and frequently modified but not changing in size. This does not happen when the filesystem is mounted with nodatacow. I''m using this as a workaround since subvolumes can''t be mounted with different options simultaneously. ie. one with

Hi, The following series of patches implements in btrfs an ioctl to do out-of-band deduplication of file extents. To be clear, this means that the file system is mounted and running, but the dedupe is not done during file writes, but after the fact when some userspace software initiates a dedupe. The primary patch is loosely based off of one sent by Josef Bacik back in January, 2011.

----- Forwarded Message ----- From: "Stefan Hajnoczi" <stefanha@redhat.com> To: "Eric Sandeen" <sandeen@redhat.com> Cc: virt-devel@redhat.com, "Kevin Wolf" <kwolf@redhat.com> Sent: Friday, November 22, 2013 9:20:51 AM Subject: [virt-devel] btrfs NOCOW for VM disk images Hi, In upstream QEMU we''re discussing patches that set the NOCOW flag

Add ''-C'' (nocow) option to vhd-util create. Btrfs has terrible performance when hosting VM images, even more when the guest in those VM are also using btrfs as file system. One way to mitigate this bad performance is to turn off COW attributes on VM files (since having copy on write for this kind of data is not useful). According to ''chattr'' manpage, NOCOW

Balance will create reloc_root for each fs root, and it''s going to record last_snapshot to filter shared blocks. The side effect of setting last_snapshot is to break nocow attributes of files. So it turns out that checking last_snapshot does not always ensure that a node/leaf/file_extent is shared. That''s why shared node/leaf needs to search extent tree for number of

V1->V2: Check to see if our current ppos is >= i_size after a short DIO read, just in case it was actually a short read and we need to just return. This is similar to what already happens in the write case. If we have a short read while doing O_DIRECT, instead of just returning, fallthrough and try to read the rest via buffered IO. BTRFS needs this because if we encounter a compressed or

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

While testing raid-auto-repair patches I''m going to send out later, I just found the very last bug in my current scrub patch series: Changelog v4->v5: - fixed a deadlock when fixup is taking longer while scrub is about to end Original message follows: ------------------------ This patch set introduces two new features for scrub. They share the backref iteration code which is the

Hi all - The following 9 patches add more error handling to the btrfs code: - Add btrfs_panic - Catch locking failures in {set,clear}_extent_bit - Push up set_extent_bit errors to callers - Push up lock_extent errors to callers - Push up clear_extent_bit errors to callers - Push up unlock_extent errors to callers - Make pin_down_extent return void - Push up btrfs_pin_extent errors to

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

I have a 3 disk raid1 filesystem mounted with nodatacow. I have a folder in said filesystem with the ''C'' NOCOW & ''Z'' Not_Compressed flags set for good measure. I then copy in a large file and proceed to make random modifications. Filefrag shows no additional extents created, good so far. A big thank you to the those devs who got that working. However, after

After running ceph on XFS for some time, I decided to try btrfs again. Performance with the current "for-linux-min" branch and big metadata is much better. The only problem (?) I''m still seeing is a warning that seems to occur from time to time: [87703.784552] ------------[ cut here ]------------ [87703.789759] WARNING: at fs/btrfs/inode.c:2103

Add a mount option user_subvol_rm_allowed that allows users to delete a (potentially non-empty!) subvol when they would otherwise we allowed to do an rmdir(2). We duplicate the may_delete() checks from the core VFS code to implement identical security checks (minus the directory size check). Signed-off-by: Sage Weil <sage@newdream.net> --- fs/btrfs/ctree.h | 1 + fs/btrfs/ioctl.c |

Hi all - Here''s my current error handling patchset, against 3.1-rc8. Almost all of this patchset is preparing for actual error handling. Before we start in on that work, I''m trying to reduce the surface we need to worry about. It turns out that there is a ton of code that returns an error code but never actually reports an error. The patchset has grown to 65 patches. 46 of them

I want to eliminate the COW feature on all of my OS files. It is a nice feature for user files, but I don''t see a clear benefit for the actual OS files. And I suspect that COW induced fragmentation is causing or aggravating problems with my system including the boot open_ctree problem. I had planned to recursively chattr these files to "nodatacow" status but then I ran

Hello, I''m using kernel 3.1.0 and I have both / and /home as btrfs. I used suspend to ram quite often and never had a problem, but yesterday I''ve suspended to get into a plane and when I resumed my /home was all about input/output errors. Reboot did not help either. My root (/) did not suffer any problems. Today I''ve upgraded btrfs-progs to latest GIT and tried scrub

What happens if you set an individual file inside a subvolume as nocow (chattr +C) and then take a snapshot of that subvolume and modify the file in both? Will btrfs now ignore the nocow attribute completely or will it do "as few copies as possible"? (I''d love to know if it''s possible to visualize the fragmentation of a single file.) -- To unsubscribe from this list:

Hello, I''m seeing a lot of warnings in dmesg with a BTRFS filesystem. I''m using the 3.1 kernel, I found a patch for these warnings ( http://marc.info/?l=linux-btrfs&m=131547325515336&w=2) <http://marc.info/?l=linux-btrfs&m=131547325515336&w=2>, but that patch has already been included in 3.1. Are there any other patches I can try? I''m using

Hello, Trying to put together a list of TODO items for btrfs so we can update the wiki page fully. So far these things are on the list * Proper ENOSPC handling * O_DIRECT support (without checksumming) * AIO support * Subvolume quotas and inherited space usage information * Snapshot removal * QA Suite for automated regression testing * Reserved space for online fsck and the ability to add

I removed this in an earlier commit and I was wrong. Because compression can return from filemap_fdatawrite() without having actually set any of it''s pages as writeback() it can make filemap_fdatawait() do essentially nothing, and then we won''t find any ordered extents because they may not have been created yet. So not only does this make fsync() completely useless, but it will