3.16.60-rc1 review patch. If anyone has any objections, please let me know.
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From: Filipe Manana fdmanana@suse.com
commit 5762b5c958abbecb7fb9f4596a6476d1ce91ecf6 upstream.
If we open a file with O_TMPFILE, don't do any further operation on it (so that the inode item isn't updated) and then force a transaction commit, we get a persisted inode item with a link count of 1, and not 0 as it should be.
Steps to reproduce it (requires a modern xfs_io with -T support):
$ mkfs.btrfs -f /dev/sdd $ mount -o /dev/sdd /mnt $ xfs_io -T /mnt & $ sync
Then btrfs-debug-tree shows the inode item with a link count of 1:
$ btrfs-debug-tree /dev/sdd (...) fs tree key (FS_TREE ROOT_ITEM 0) leaf 29556736 items 4 free space 15851 generation 6 owner 5 fs uuid f164d01b-1b92-481d-a4e4-435fb0f843d0 chunk uuid 0e3d0e56-bcca-4a1c-aa5f-cec2c6f4f7a6 item 0 key (256 INODE_ITEM 0) itemoff 16123 itemsize 160 inode generation 3 transid 6 size 0 block group 0 mode 40755 links 1 item 1 key (256 INODE_REF 256) itemoff 16111 itemsize 12 inode ref index 0 namelen 2 name: .. item 2 key (257 INODE_ITEM 0) itemoff 15951 itemsize 160 inode generation 6 transid 6 size 0 block group 0 mode 100600 links 1 item 3 key (ORPHAN ORPHAN_ITEM 257) itemoff 15951 itemsize 0 orphan item checksum tree key (CSUM_TREE ROOT_ITEM 0) (...)
Signed-off-by: Filipe Manana fdmanana@suse.com Signed-off-by: Chris Mason clm@fb.com Signed-off-by: Ben Hutchings ben@decadent.org.uk --- fs/btrfs/inode.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+)
--- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -5731,6 +5731,13 @@ static struct inode *btrfs_new_inode(str }
/* + * O_TMPFILE, set link count to 0, so that after this point, + * we fill in an inode item with the correct link count. + */ + if (!name) + set_nlink(inode, 0); + + /* * we have to initialize this early, so we can reclaim the inode * number if we fail afterwards in this function. */ @@ -9096,6 +9103,14 @@ static int btrfs_tmpfile(struct inode *d if (ret) goto out;
+ /* + * We set number of links to 0 in btrfs_new_inode(), and here we set + * it to 1 because d_tmpfile() will issue a warning if the count is 0, + * through: + * + * d_tmpfile() -> inode_dec_link_count() -> drop_nlink() + */ + set_nlink(inode, 1); d_tmpfile(dentry, inode); mark_inode_dirty(inode);