Re: [PATCH] Btrfs: fix sync fs to actually wait for all data to be persisted
On Mon, Sep 23, 2013 at 10:11:42AM +0100, Filipe David Manana wrote: > On Mon, Sep 23, 2013 at 2:30 AM, Miao Xie wrote: > > > > On sun, 22 Sep 2013 21:55:53 +0100, Filipe David Borba Manana wrote: > > > Currently the fs sync function (super.c:btrfs_sync_fs()) doesn't > > > wait for delayed work to finish before returning success to the > > > caller. This change fixes this, ensuring that there's no data loss > > > if a power failure happens right after fs sync returns success to > > > the caller and before the next commit happens. > > > > > > Steps to reproduce the data loss issue: > > > > > > $ mkfs.btrfs -f /dev/sdb3 > > > $ mount /dev/sdb3 /mnt/btrfs > > > $ perl -e '$d = ("\x41" x 6001); open($f,">","/mnt/btrfs/foobar"); print > > > $f $d; close($f);' && btrfs fi sync /mnt/btrfs > > > > > > Right after the btrfs fi sync command (a second or 2 for example), power > > > off the machine and reboot it. The file will be empty, as it can be > > > verified > > > after mounting the filesystem and through btrfs-debug-tree: > > > > > > $ btrfs-debug-tree /dev/sdb3 | egrep '\(257 INODE_ITEM 0\) itemoff' -B 3 > > > -A 8 > > > > > > item 3 key (256 DIR_INDEX 2) itemoff 3751 itemsize 36 > > > location key (257 INODE_ITEM 0) type FILE > > > namelen 6 datalen 0 name: foobar > > > item 4 key (257 INODE_ITEM 0) itemoff 3591 itemsize 160 > > > inode generation 7 transid 7 size 0 block group 0 mode > > > 100644 links 1 > > > item 5 key (257 INODE_REF 256) itemoff 3575 itemsize 16 > > > inode ref index 2 namelen 6 name: foobar > > > checksum tree key (CSUM_TREE ROOT_ITEM 0) > > > leaf 29429760 items 0 free space 3995 generation 7 owner 7 > > > fs uuid 6192815c-af2a-4b75-b3db-a959ffb6166e > > > chunk uuid b529c44b-938c-4d3d-910a-013b4700bcae > > > uuid tree key (UUID_TREE ROOT_ITEM 0) > > > > > > After this patch, the data loss no longer happens after a power failure > > > and > > > btrfs-debug-tree shows: > > > > > > $ btrfs-debug-tree /dev/sdb3 | egrep '\(257 INODE_ITEM 0\) itemoff' -B 3 > > > -A 8 > > > item 3 key (256 DIR_INDEX 2) itemoff 3751 itemsize 36 > > > location key (257 INODE_ITEM 0) type FILE > > > namelen 6 datalen 0 name: foobar > > > item 4 key (257 INODE_ITEM 0) itemoff 3591 itemsize 160 > > > inode generation 6 transid 6 size 6001 block group 0 mode > > > 100644 links 1 > > > item 5 key (257 INODE_REF 256) itemoff 3575 itemsize 16 > > > inode ref index 2 namelen 6 name: foobar > > > item 6 key (257 EXTENT_DATA 0) itemoff 3522 itemsize 53 > > > extent data disk byte 12845056 nr 8192 > > > extent data offset 0 nr 8192 ram 8192 > > > extent compression 0 > > > checksum tree key (CSUM_TREE ROOT_ITEM 0) > > > > > > Signed-off-by: Filipe David Borba Manana > > > --- > > > fs/btrfs/super.c |5 + > > > 1 file changed, 5 insertions(+) > > > > > > diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c > > > index 6ab0df5..557e38f 100644 > > > --- a/fs/btrfs/super.c > > > +++ b/fs/btrfs/super.c > > > @@ -913,6 +913,7 @@ int btrfs_sync_fs(struct super_block *sb, int wait) > > > struct btrfs_trans_handle *trans; > > > struct btrfs_fs_info *fs_info = btrfs_sb(sb); > > > struct btrfs_root *root = fs_info->tree_root; > > > + int ret; > > > > > > trace_btrfs_sync_fs(wait); > > > > > > @@ -921,6 +922,10 @@ int btrfs_sync_fs(struct super_block *sb, int wait) > > > return 0; > > > } > > > > > > + ret = btrfs_start_all_delalloc_inodes(fs_info, 0); > > > + if (ret) > > > + return ret; > > > + > > > > I don't think we should call btrfs_start_all_delalloc_inodes(), because > > this function is also > > called by do_sync(), but do_sync() syncs the whole fs before calling it, so > > if we add > > btrfs_start_all_delalloc_inodes() here, we will sync the fs twice, and the > > second one is unnecessary. > > Where is that do_sync() function exactly? I'm not finding any with > that exact name in fs/btrfs/* nor fs/* I think it should refer to sync_filesystem() :) -liubo -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] Btrfs: fix sync fs to actually wait for all data to be persisted
On Mon, Sep 23, 2013 at 2:30 AM, Miao Xie wrote: > > On sun, 22 Sep 2013 21:55:53 +0100, Filipe David Borba Manana wrote: > > Currently the fs sync function (super.c:btrfs_sync_fs()) doesn't > > wait for delayed work to finish before returning success to the > > caller. This change fixes this, ensuring that there's no data loss > > if a power failure happens right after fs sync returns success to > > the caller and before the next commit happens. > > > > Steps to reproduce the data loss issue: > > > > $ mkfs.btrfs -f /dev/sdb3 > > $ mount /dev/sdb3 /mnt/btrfs > > $ perl -e '$d = ("\x41" x 6001); open($f,">","/mnt/btrfs/foobar"); print $f > > $d; close($f);' && btrfs fi sync /mnt/btrfs > > > > Right after the btrfs fi sync command (a second or 2 for example), power > > off the machine and reboot it. The file will be empty, as it can be verified > > after mounting the filesystem and through btrfs-debug-tree: > > > > $ btrfs-debug-tree /dev/sdb3 | egrep '\(257 INODE_ITEM 0\) itemoff' -B 3 -A > > 8 > > > > item 3 key (256 DIR_INDEX 2) itemoff 3751 itemsize 36 > > location key (257 INODE_ITEM 0) type FILE > > namelen 6 datalen 0 name: foobar > > item 4 key (257 INODE_ITEM 0) itemoff 3591 itemsize 160 > > inode generation 7 transid 7 size 0 block group 0 mode > > 100644 links 1 > > item 5 key (257 INODE_REF 256) itemoff 3575 itemsize 16 > > inode ref index 2 namelen 6 name: foobar > > checksum tree key (CSUM_TREE ROOT_ITEM 0) > > leaf 29429760 items 0 free space 3995 generation 7 owner 7 > > fs uuid 6192815c-af2a-4b75-b3db-a959ffb6166e > > chunk uuid b529c44b-938c-4d3d-910a-013b4700bcae > > uuid tree key (UUID_TREE ROOT_ITEM 0) > > > > After this patch, the data loss no longer happens after a power failure and > > btrfs-debug-tree shows: > > > > $ btrfs-debug-tree /dev/sdb3 | egrep '\(257 INODE_ITEM 0\) itemoff' -B 3 -A > > 8 > > item 3 key (256 DIR_INDEX 2) itemoff 3751 itemsize 36 > > location key (257 INODE_ITEM 0) type FILE > > namelen 6 datalen 0 name: foobar > > item 4 key (257 INODE_ITEM 0) itemoff 3591 itemsize 160 > > inode generation 6 transid 6 size 6001 block group 0 mode > > 100644 links 1 > > item 5 key (257 INODE_REF 256) itemoff 3575 itemsize 16 > > inode ref index 2 namelen 6 name: foobar > > item 6 key (257 EXTENT_DATA 0) itemoff 3522 itemsize 53 > > extent data disk byte 12845056 nr 8192 > > extent data offset 0 nr 8192 ram 8192 > > extent compression 0 > > checksum tree key (CSUM_TREE ROOT_ITEM 0) > > > > Signed-off-by: Filipe David Borba Manana > > --- > > fs/btrfs/super.c |5 + > > 1 file changed, 5 insertions(+) > > > > diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c > > index 6ab0df5..557e38f 100644 > > --- a/fs/btrfs/super.c > > +++ b/fs/btrfs/super.c > > @@ -913,6 +913,7 @@ int btrfs_sync_fs(struct super_block *sb, int wait) > > struct btrfs_trans_handle *trans; > > struct btrfs_fs_info *fs_info = btrfs_sb(sb); > > struct btrfs_root *root = fs_info->tree_root; > > + int ret; > > > > trace_btrfs_sync_fs(wait); > > > > @@ -921,6 +922,10 @@ int btrfs_sync_fs(struct super_block *sb, int wait) > > return 0; > > } > > > > + ret = btrfs_start_all_delalloc_inodes(fs_info, 0); > > + if (ret) > > + return ret; > > + > > I don't think we should call btrfs_start_all_delalloc_inodes(), because this > function is also > called by do_sync(), but do_sync() syncs the whole fs before calling it, so > if we add > btrfs_start_all_delalloc_inodes() here, we will sync the fs twice, and the > second one is unnecessary. Where is that do_sync() function exactly? I'm not finding any with that exact name in fs/btrfs/* nor fs/* I used this approach because (besides working) it's what is done in btrfs_commit_transaction() (via btrfs_start_delalloc_flush and btrfs_wait_delalloc_flush). Why can it be like that in the transaction commit and not in btrfs_sync_fs() ? > > Calling writeback_inodes_sb() before btrfs_sync_fs() is better way to fix > this problem. Just tested it, and it works that way too. Uploading a new patch. Thanks for the feedback/review Miao. > > Thanks > Miao > > > btrfs_wait_all_ordered_extents(fs_info); > > > > trans = btrfs_attach_transaction_barrier(root); > > > -- Filipe David Manana, "Reasonable men adapt themselves to the world. Unreasonable men adapt the world to themselves. That's why all progress depends on unreasonable men." -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] Btrfs: fix sync fs to actually wait for all data to be persisted
On sun, 22 Sep 2013 21:55:53 +0100, Filipe David Borba Manana wrote: > Currently the fs sync function (super.c:btrfs_sync_fs()) doesn't > wait for delayed work to finish before returning success to the > caller. This change fixes this, ensuring that there's no data loss > if a power failure happens right after fs sync returns success to > the caller and before the next commit happens. > > Steps to reproduce the data loss issue: > > $ mkfs.btrfs -f /dev/sdb3 > $ mount /dev/sdb3 /mnt/btrfs > $ perl -e '$d = ("\x41" x 6001); open($f,">","/mnt/btrfs/foobar"); print $f > $d; close($f);' && btrfs fi sync /mnt/btrfs > > Right after the btrfs fi sync command (a second or 2 for example), power > off the machine and reboot it. The file will be empty, as it can be verified > after mounting the filesystem and through btrfs-debug-tree: > > $ btrfs-debug-tree /dev/sdb3 | egrep '\(257 INODE_ITEM 0\) itemoff' -B 3 -A 8 > > item 3 key (256 DIR_INDEX 2) itemoff 3751 itemsize 36 > location key (257 INODE_ITEM 0) type FILE > namelen 6 datalen 0 name: foobar > item 4 key (257 INODE_ITEM 0) itemoff 3591 itemsize 160 > inode generation 7 transid 7 size 0 block group 0 mode 100644 > links 1 > item 5 key (257 INODE_REF 256) itemoff 3575 itemsize 16 > inode ref index 2 namelen 6 name: foobar > checksum tree key (CSUM_TREE ROOT_ITEM 0) > leaf 29429760 items 0 free space 3995 generation 7 owner 7 > fs uuid 6192815c-af2a-4b75-b3db-a959ffb6166e > chunk uuid b529c44b-938c-4d3d-910a-013b4700bcae > uuid tree key (UUID_TREE ROOT_ITEM 0) > > After this patch, the data loss no longer happens after a power failure and > btrfs-debug-tree shows: > > $ btrfs-debug-tree /dev/sdb3 | egrep '\(257 INODE_ITEM 0\) itemoff' -B 3 -A 8 > item 3 key (256 DIR_INDEX 2) itemoff 3751 itemsize 36 > location key (257 INODE_ITEM 0) type FILE > namelen 6 datalen 0 name: foobar > item 4 key (257 INODE_ITEM 0) itemoff 3591 itemsize 160 > inode generation 6 transid 6 size 6001 block group 0 mode > 100644 links 1 > item 5 key (257 INODE_REF 256) itemoff 3575 itemsize 16 > inode ref index 2 namelen 6 name: foobar > item 6 key (257 EXTENT_DATA 0) itemoff 3522 itemsize 53 > extent data disk byte 12845056 nr 8192 > extent data offset 0 nr 8192 ram 8192 > extent compression 0 > checksum tree key (CSUM_TREE ROOT_ITEM 0) > > Signed-off-by: Filipe David Borba Manana > --- > fs/btrfs/super.c |5 + > 1 file changed, 5 insertions(+) > > diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c > index 6ab0df5..557e38f 100644 > --- a/fs/btrfs/super.c > +++ b/fs/btrfs/super.c > @@ -913,6 +913,7 @@ int btrfs_sync_fs(struct super_block *sb, int wait) > struct btrfs_trans_handle *trans; > struct btrfs_fs_info *fs_info = btrfs_sb(sb); > struct btrfs_root *root = fs_info->tree_root; > + int ret; > > trace_btrfs_sync_fs(wait); > > @@ -921,6 +922,10 @@ int btrfs_sync_fs(struct super_block *sb, int wait) > return 0; > } > > + ret = btrfs_start_all_delalloc_inodes(fs_info, 0); > + if (ret) > + return ret; > + I don't think we should call btrfs_start_all_delalloc_inodes(), because this function is also called by do_sync(), but do_sync() syncs the whole fs before calling it, so if we add btrfs_start_all_delalloc_inodes() here, we will sync the fs twice, and the second one is unnecessary. Calling writeback_inodes_sb() before btrfs_sync_fs() is better way to fix this problem. Thanks Miao > btrfs_wait_all_ordered_extents(fs_info); > > trans = btrfs_attach_transaction_barrier(root); > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
[PATCH] Btrfs: fix sync fs to actually wait for all data to be persisted
Currently the fs sync function (super.c:btrfs_sync_fs()) doesn't wait for delayed work to finish before returning success to the caller. This change fixes this, ensuring that there's no data loss if a power failure happens right after fs sync returns success to the caller and before the next commit happens. Steps to reproduce the data loss issue: $ mkfs.btrfs -f /dev/sdb3 $ mount /dev/sdb3 /mnt/btrfs $ perl -e '$d = ("\x41" x 6001); open($f,">","/mnt/btrfs/foobar"); print $f $d; close($f);' && btrfs fi sync /mnt/btrfs Right after the btrfs fi sync command (a second or 2 for example), power off the machine and reboot it. The file will be empty, as it can be verified after mounting the filesystem and through btrfs-debug-tree: $ btrfs-debug-tree /dev/sdb3 | egrep '\(257 INODE_ITEM 0\) itemoff' -B 3 -A 8 item 3 key (256 DIR_INDEX 2) itemoff 3751 itemsize 36 location key (257 INODE_ITEM 0) type FILE namelen 6 datalen 0 name: foobar item 4 key (257 INODE_ITEM 0) itemoff 3591 itemsize 160 inode generation 7 transid 7 size 0 block group 0 mode 100644 links 1 item 5 key (257 INODE_REF 256) itemoff 3575 itemsize 16 inode ref index 2 namelen 6 name: foobar checksum tree key (CSUM_TREE ROOT_ITEM 0) leaf 29429760 items 0 free space 3995 generation 7 owner 7 fs uuid 6192815c-af2a-4b75-b3db-a959ffb6166e chunk uuid b529c44b-938c-4d3d-910a-013b4700bcae uuid tree key (UUID_TREE ROOT_ITEM 0) After this patch, the data loss no longer happens after a power failure and btrfs-debug-tree shows: $ btrfs-debug-tree /dev/sdb3 | egrep '\(257 INODE_ITEM 0\) itemoff' -B 3 -A 8 item 3 key (256 DIR_INDEX 2) itemoff 3751 itemsize 36 location key (257 INODE_ITEM 0) type FILE namelen 6 datalen 0 name: foobar item 4 key (257 INODE_ITEM 0) itemoff 3591 itemsize 160 inode generation 6 transid 6 size 6001 block group 0 mode 100644 links 1 item 5 key (257 INODE_REF 256) itemoff 3575 itemsize 16 inode ref index 2 namelen 6 name: foobar item 6 key (257 EXTENT_DATA 0) itemoff 3522 itemsize 53 extent data disk byte 12845056 nr 8192 extent data offset 0 nr 8192 ram 8192 extent compression 0 checksum tree key (CSUM_TREE ROOT_ITEM 0) Signed-off-by: Filipe David Borba Manana --- fs/btrfs/super.c |5 + 1 file changed, 5 insertions(+) diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c index 6ab0df5..557e38f 100644 --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -913,6 +913,7 @@ int btrfs_sync_fs(struct super_block *sb, int wait) struct btrfs_trans_handle *trans; struct btrfs_fs_info *fs_info = btrfs_sb(sb); struct btrfs_root *root = fs_info->tree_root; + int ret; trace_btrfs_sync_fs(wait); @@ -921,6 +922,10 @@ int btrfs_sync_fs(struct super_block *sb, int wait) return 0; } + ret = btrfs_start_all_delalloc_inodes(fs_info, 0); + if (ret) + return ret; + btrfs_wait_all_ordered_extents(fs_info); trans = btrfs_attach_transaction_barrier(root); -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html