similar to: [PATCH] New nodatacow checker

Hello, This patch fixes the nodatacow check. The new test function can always detect extents referenced by multiple snatshots. If a extent was allocated in recent two transactions and no snapshot happened in these two transactions, we can always avoid cow. To check given extent''s reference, the test function walks down old tree root, then check backref info in the path. This initial

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

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

To reproduce the bug: # mount -o nodatacow /dev/sda7 /mnt/ # dd if=/dev/zero of=/mnt/tmp bs=4K count=1 1+0 records in 1+0 records out 4096 bytes (4.1 kB) copied, 0.000136115 s, 30.1 MB/s # dd if=/dev/zero of=/mnt/tmp bs=4K count=1 conv=notrunc oflag=direct dd: writing `/mnt/tmp'': Input/output error 1+0 records in 0+0 records out btrfs_ordered_update_i_size() may return

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 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, This patch simplifies the nodatacow checker. If all references were created after the latest snapshot, then we can avoid COW safely. This patch also updates run_delalloc_nocow to do more fine-grained checking. Regards Signed-off-by: Yan Zheng <zheng.yan@oracle.com> --- diff -urp 3/fs/btrfs/ctree.h 4/fs/btrfs/ctree.h --- 3/fs/btrfs/ctree.h 2008-10-27 16:31:51.000000000 +0800 +++

Hi Seto, please could you update also the man page too ? Why it was not provided a way to clear a *single* flag ? To me it seems a bit too long to clear all the flag (btrfs mount-option clear) and then set the right one. As user interface I suggest something like chmod: btrfs mount-option set +ssd,skip_balance -nodatacow /dev/sdX or btrfs mount-option set =ssd,skip_balance,nodatacow

My static checker complains that this sprintf() can overflow but really it can't. Just silence the warning by using snprintf(). Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com> --- v2: the overflow is not possible so just leave the buffer size alone and silence the warning with snprintf(). diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c index

My static checker complains that this sprintf() can overflow but really it can't. Just silence the warning by using snprintf(). Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com> --- v2: the overflow is not possible so just leave the buffer size alone and silence the warning with snprintf(). diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c index

I need everybody to go over this with a fine toothed comb since it is a pretty big change. I think it is right and it seems to come out right, but if it''s not it will mean we screw up O_DIRECT on snapshotted files with preallocated extents, so please, make sure it is correct :). --- Subject: [PATCH] Btrfs: rework can_nocow_odirect We are always doing the file extent lookup in here

Hi, If i set strict allocate = yes in samba to speed up the transfer of a mssql database dump, then btrfs does not compress the file. I have tried it also by just copying a small file in Windows to the samba share and the same. I have tried btrfs mount options autodefrag and then btrfs fi defrag -c and the file still does not get compressed. I have tried kernels 3.6.11, 3.8 and 3.10.7 on FC16

Hi, I am using 2.6.36.3 kernel with btrfs, 512MB memory and a very slow disk, no special options for mounting btrfs except noatime. Now I found it very slow. When I rm a 5GB movie, it took 20 secs. -- 竹密岂妨流水过 山高哪阻野云飞 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at

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

Christoph Hellwig wrote: > There are a lot of variables when using qemu. > > The most important one are: > > - the cache mode on the device. The default is cache=writethrough, > which is not quite optimal. You generally do want to use cache=none > which uses O_DIRECT in qemu. > - if the backing image is sparse or not. > - if you use barrier - both in the host

Hello, some time ago we discussed on #btrfs that the nocow attribute for files wasn''t working (around 3.3 or 3.4 kernels). That was evident by files fragmenting even with the attribute set. Chris mentioned to find a fix quickly for that, and posted some lines of change into irc. But recently someone mentioned that 3.6-rc looks like still not respecting nocow for files. Is there really

What are the recommendations for running KVM images on BTRFS systems using kernel 3.4?  I saw older posts on the web complaining about poor performance, but I know a lot of work has gone into btrfs since then.  There also seemed to be the nocow option, but I didn''t find anything that said it actualy helped. Anybody have ideas? Thanks, Matt -- To unsubscribe from this list: send the line

Am 08.05.2015 11:16, schrieb Dan Carpenter: > My static checker complains that this sprintf() can overflow but really > it can't. Just silence the warning by using snprintf(). > > Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com> > --- > v2: the overflow is not possible so just leave the buffer size alone and > silence the warning with snprintf(). >

----- 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

I''m new to Ruby and RoR; I was messing around with it today and had trouble with error codes. Specifically, the ruby syntax checker frequently spits out ''syntax error'' with the last line of the code as the error line (the error is nowhere near the last line). This is something I''d expect in a pre 1.0 version, but ruby is at 1.8.4, is the ruby syntax