Re: [PATCH] btrfs: skip file_extent generation check for free_space_inode in run_delalloc_nocow
On Thu, Nov 29, 2018 at 05:31:32PM +0800, Lu Fengqi wrote:
> The btrfs/001 with inode_cache mount option will encounter the following
> warning:
>
> WARNING: CPU: 1 PID: 23700 at fs/btrfs/inode.c:956
> cow_file_range.isra.19+0x32b/0x430 [btrfs]
> CPU: 1 PID: 23700 Comm: btrfs Kdump: loaded Tainted: GW O
> 4.20.0-rc4-custom+ #30
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
> RIP: 0010:cow_file_range.isra.19+0x32b/0x430 [btrfs]
> Call Trace:
> ? free_extent_buffer+0x46/0x90 [btrfs]
> run_delalloc_nocow+0x455/0x900 [btrfs]
> btrfs_run_delalloc_range+0x1a7/0x360 [btrfs]
> writepage_delalloc+0xf9/0x150 [btrfs]
> __extent_writepage+0x125/0x3e0 [btrfs]
> extent_write_cache_pages+0x1b6/0x3e0 [btrfs]
> ? __wake_up_common_lock+0x63/0xc0
> extent_writepages+0x50/0x80 [btrfs]
> do_writepages+0x41/0xd0
> ? __filemap_fdatawrite_range+0x9e/0xf0
> __filemap_fdatawrite_range+0xbe/0xf0
> btrfs_fdatawrite_range+0x1b/0x50 [btrfs]
> __btrfs_write_out_cache+0x42c/0x480 [btrfs]
> btrfs_write_out_ino_cache+0x84/0xd0 [btrfs]
> btrfs_save_ino_cache+0x551/0x660 [btrfs]
> commit_fs_roots+0xc5/0x190 [btrfs]
> btrfs_commit_transaction+0x2bf/0x8d0 [btrfs]
> btrfs_mksubvol+0x48d/0x4d0 [btrfs]
> btrfs_ioctl_snap_create_transid+0x170/0x180 [btrfs]
> btrfs_ioctl_snap_create_v2+0x124/0x180 [btrfs]
> btrfs_ioctl+0x123f/0x3030 [btrfs]
>
> The file extent generation of the free space inode is equal to the last
> snapshot of the file root, so the inode will be passed to cow_file_rage.
> But the inode was created and its extents were preallocated in
> btrfs_save_ino_cache, there are no cow copies on disk.
>
> The preallocated extents don't present on disk, and the
> btrfs_cross_ref_exist will ignore the -ENOENT returned by
> check_committed_ref, so we can directly write the inode to the disk.
>
> Fixes: 78d4295b1eee ("btrfs: lift some btrfs_cross_ref_exist checks in nocow
> path")
> Signed-off-by: Lu Fengqi
With updated changelog and reviewed-by added to misc-next, thanks.
Re: [PATCH] btrfs: skip file_extent generation check for free_space_inode in run_delalloc_nocow
On Thu, Nov 29, 2018 at 9:32 AM Lu Fengqi wrote:
>
> The btrfs/001 with inode_cache mount option will encounter the following
> warning:
"The test case btrfs/001 ..."
>
> WARNING: CPU: 1 PID: 23700 at fs/btrfs/inode.c:956
> cow_file_range.isra.19+0x32b/0x430 [btrfs]
> CPU: 1 PID: 23700 Comm: btrfs Kdump: loaded Tainted: GW O
> 4.20.0-rc4-custom+ #30
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
> RIP: 0010:cow_file_range.isra.19+0x32b/0x430 [btrfs]
> Call Trace:
> ? free_extent_buffer+0x46/0x90 [btrfs]
> run_delalloc_nocow+0x455/0x900 [btrfs]
> btrfs_run_delalloc_range+0x1a7/0x360 [btrfs]
> writepage_delalloc+0xf9/0x150 [btrfs]
> __extent_writepage+0x125/0x3e0 [btrfs]
> extent_write_cache_pages+0x1b6/0x3e0 [btrfs]
> ? __wake_up_common_lock+0x63/0xc0
> extent_writepages+0x50/0x80 [btrfs]
> do_writepages+0x41/0xd0
> ? __filemap_fdatawrite_range+0x9e/0xf0
> __filemap_fdatawrite_range+0xbe/0xf0
> btrfs_fdatawrite_range+0x1b/0x50 [btrfs]
> __btrfs_write_out_cache+0x42c/0x480 [btrfs]
> btrfs_write_out_ino_cache+0x84/0xd0 [btrfs]
> btrfs_save_ino_cache+0x551/0x660 [btrfs]
> commit_fs_roots+0xc5/0x190 [btrfs]
> btrfs_commit_transaction+0x2bf/0x8d0 [btrfs]
> btrfs_mksubvol+0x48d/0x4d0 [btrfs]
> btrfs_ioctl_snap_create_transid+0x170/0x180 [btrfs]
> btrfs_ioctl_snap_create_v2+0x124/0x180 [btrfs]
> btrfs_ioctl+0x123f/0x3030 [btrfs]
>
> The file extent generation of the free space inode is equal to the last
> snapshot of the file root, so the inode will be passed to cow_file_rage.
> But the inode was created and its extents were preallocated in
> btrfs_save_ino_cache, there are no cow copies on disk.
>
> The preallocated extents don't present on disk, and the
The preallocated extent is not yet in the extent tree, and the ...
(singular, it's only used for each space cache)
> btrfs_cross_ref_exist will ignore the -ENOENT returned by
> check_committed_ref, so we can directly write the inode to the disk.
>
> Fixes: 78d4295b1eee ("btrfs: lift some btrfs_cross_ref_exist checks in nocow
> path")
> Signed-off-by: Lu Fengqi
The code changes look good to me.
Reviewed-by: Filipe Manana
Thanks.
> ---
> fs/btrfs/inode.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index d54bdef16d8d..9c5e9629eb6c 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -1369,7 +1369,8 @@ static noinline int run_delalloc_nocow(struct inode
> *inode,
> * Do the same check as in btrfs_cross_ref_exist but
> * without the unnecessary search.
> */
> - if (btrfs_file_extent_generation(leaf, fi) <=
> + if (!nolock &&
> + btrfs_file_extent_generation(leaf, fi) <=
> btrfs_root_last_snapshot(>root_item))
> goto out_check;
> if (extent_type == BTRFS_FILE_EXTENT_REG && !force)
> --
> 2.19.2
>
>
>
--
Filipe David Manana,
“Whether you think you can, or you think you can't — you're right.”
[PATCH] btrfs: skip file_extent generation check for free_space_inode in run_delalloc_nocow
The btrfs/001 with inode_cache mount option will encounter the following
warning:
WARNING: CPU: 1 PID: 23700 at fs/btrfs/inode.c:956
cow_file_range.isra.19+0x32b/0x430 [btrfs]
CPU: 1 PID: 23700 Comm: btrfs Kdump: loaded Tainted: GW O
4.20.0-rc4-custom+ #30
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
RIP: 0010:cow_file_range.isra.19+0x32b/0x430 [btrfs]
Call Trace:
? free_extent_buffer+0x46/0x90 [btrfs]
run_delalloc_nocow+0x455/0x900 [btrfs]
btrfs_run_delalloc_range+0x1a7/0x360 [btrfs]
writepage_delalloc+0xf9/0x150 [btrfs]
__extent_writepage+0x125/0x3e0 [btrfs]
extent_write_cache_pages+0x1b6/0x3e0 [btrfs]
? __wake_up_common_lock+0x63/0xc0
extent_writepages+0x50/0x80 [btrfs]
do_writepages+0x41/0xd0
? __filemap_fdatawrite_range+0x9e/0xf0
__filemap_fdatawrite_range+0xbe/0xf0
btrfs_fdatawrite_range+0x1b/0x50 [btrfs]
__btrfs_write_out_cache+0x42c/0x480 [btrfs]
btrfs_write_out_ino_cache+0x84/0xd0 [btrfs]
btrfs_save_ino_cache+0x551/0x660 [btrfs]
commit_fs_roots+0xc5/0x190 [btrfs]
btrfs_commit_transaction+0x2bf/0x8d0 [btrfs]
btrfs_mksubvol+0x48d/0x4d0 [btrfs]
btrfs_ioctl_snap_create_transid+0x170/0x180 [btrfs]
btrfs_ioctl_snap_create_v2+0x124/0x180 [btrfs]
btrfs_ioctl+0x123f/0x3030 [btrfs]
The file extent generation of the free space inode is equal to the last
snapshot of the file root, so the inode will be passed to cow_file_rage.
But the inode was created and its extents were preallocated in
btrfs_save_ino_cache, there are no cow copies on disk.
The preallocated extents don't present on disk, and the
btrfs_cross_ref_exist will ignore the -ENOENT returned by
check_committed_ref, so we can directly write the inode to the disk.
Fixes: 78d4295b1eee ("btrfs: lift some btrfs_cross_ref_exist checks in nocow
path")
Signed-off-by: Lu Fengqi
---
fs/btrfs/inode.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index d54bdef16d8d..9c5e9629eb6c 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1369,7 +1369,8 @@ static noinline int run_delalloc_nocow(struct inode
*inode,
* Do the same check as in btrfs_cross_ref_exist but
* without the unnecessary search.
*/
- if (btrfs_file_extent_generation(leaf, fi) <=
+ if (!nolock &&
+ btrfs_file_extent_generation(leaf, fi) <=
btrfs_root_last_snapshot(>root_item))
goto out_check;
if (extent_type == BTRFS_FILE_EXTENT_REG && !force)
--
2.19.2
