diff options
| -rw-r--r-- | fs/xfs/xfs_inode.c | 72 |
1 files changed, 44 insertions, 28 deletions
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c index 326b94d..001aa89 100644 --- a/fs/xfs/xfs_inode.c +++ b/fs/xfs/xfs_inode.c @@ -2404,6 +2404,33 @@ xfs_iunpin_wait( __xfs_iunpin_wait(ip); } +/* + * Removing an inode from the namespace involves removing the directory entry + * and dropping the link count on the inode. Removing the directory entry can + * result in locking an AGF (directory blocks were freed) and removing a link + * count can result in placing the inode on an unlinked list which results in + * locking an AGI. + * + * The big problem here is that we have an ordering constraint on AGF and AGI + * locking - inode allocation locks the AGI, then can allocate a new extent for + * new inodes, locking the AGF after the AGI. Similarly, freeing the inode + * removes the inode from the unlinked list, requiring that we lock the AGI + * first, and then freeing the inode can result in an inode chunk being freed + * and hence freeing disk space requiring that we lock an AGF. + * + * Hence the ordering that is imposed by other parts of the code is AGI before + * AGF. This means we cannot remove the directory entry before we drop the inode + * reference count and put it on the unlinked list as this results in a lock + * order of AGF then AGI, and this can deadlock against inode allocation and + * freeing. Therefore we must drop the link counts before we remove the + * directory entry. + * + * This is still safe from a transactional point of view - it is not until we + * get to xfs_bmap_finish() that we have the possibility of multiple + * transactions in this operation. Hence as long as we remove the directory + * entry and drop the link count in the first transaction of the remove + * operation, there are no transactional constraints on the ordering here. + */ int xfs_remove( xfs_inode_t *dp, @@ -2473,6 +2500,7 @@ xfs_remove( /* * If we're removing a directory perform some additional validation. */ + cancel_flags |= XFS_TRANS_ABORT; if (is_dir) { ASSERT(ip->i_d.di_nlink >= 2); if (ip->i_d.di_nlink != 2) { @@ -2483,31 +2511,16 @@ xfs_remove( error = XFS_ERROR(ENOTEMPTY); goto out_trans_cancel; } - } - xfs_bmap_init(&free_list, &first_block); - error = xfs_dir_removename(tp, dp, name, ip->i_ino, - &first_block, &free_list, resblks); - if (error) { - ASSERT(error != ENOENT); - goto out_bmap_cancel; - } - xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG); - - if (is_dir) { - /* - * Drop the link from ip's "..". - */ + /* Drop the link from ip's "..". */ error = xfs_droplink(tp, dp); if (error) - goto out_bmap_cancel; + goto out_trans_cancel; - /* - * Drop the "." link from ip to self. - */ + /* Drop the "." link from ip to self. */ error = xfs_droplink(tp, ip); if (error) - goto out_bmap_cancel; + goto out_trans_cancel; } else { /* * When removing a non-directory we need to log the parent @@ -2516,20 +2529,24 @@ xfs_remove( */ xfs_trans_log_inode(tp, dp, XFS_ILOG_CORE); } + xfs_trans_ichgtime(tp, dp, XFS_ICHGTIME_MOD | XFS_ICHGTIME_CHG); - /* - * Drop the link from dp to ip. - */ + /* Drop the link from dp to ip. */ error = xfs_droplink(tp, ip); if (error) - goto out_bmap_cancel; + goto out_trans_cancel; - /* - * Determine if this is the last link while - * we are in the transaction. - */ + /* Determine if this is the last link while the inode is locked */ link_zero = (ip->i_d.di_nlink == 0); + xfs_bmap_init(&free_list, &first_block); + error = xfs_dir_removename(tp, dp, name, ip->i_ino, + &first_block, &free_list, resblks); + if (error) { + ASSERT(error != ENOENT); + goto out_bmap_cancel; + } + /* * If this is a synchronous mount, make sure that the * remove transaction goes to disk before returning to @@ -2559,7 +2576,6 @@ xfs_remove( out_bmap_cancel: xfs_bmap_cancel(&free_list); - cancel_flags |= XFS_TRANS_ABORT; out_trans_cancel: xfs_trans_cancel(tp, cancel_flags); std_return: |
