We did not allow file data clone within the same file because of deadlock issues. However, we now use nested lock to avoid deadlock between the parent directory and the child file. So it''s safe to do file clone within the same file when the two ranges are not overlapped. Signed-off-by: Liu Bo <bo.li.liu@oracle.com> --- v2: add sanity check for overlapping range. fs/btrfs/ioctl.c | 26 +++++++++++++++++++------- 1 files changed, 19 insertions(+), 7 deletions(-) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 898c572..69cd80d 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -2473,6 +2473,7 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd, int ret; u64 len = olen; u64 bs = root->fs_info->sb->s_blocksize; + int same_inode = 0; /* * TODO: @@ -2509,7 +2510,7 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd, ret = -EINVAL; if (src == inode) - goto out_fput; + same_inode = 1; /* the src must be open for reading */ if (!(src_file.file->f_mode & FMODE_READ)) @@ -2540,12 +2541,16 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd, } path->reada = 2; - if (inode < src) { - mutex_lock_nested(&inode->i_mutex, I_MUTEX_PARENT); - mutex_lock_nested(&src->i_mutex, I_MUTEX_CHILD); + if (!same_inode) { + if (inode < src) { + mutex_lock_nested(&inode->i_mutex, I_MUTEX_PARENT); + mutex_lock_nested(&src->i_mutex, I_MUTEX_CHILD); + } else { + mutex_lock_nested(&src->i_mutex, I_MUTEX_PARENT); + mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD); + } } else { - mutex_lock_nested(&src->i_mutex, I_MUTEX_PARENT); - mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD); + mutex_lock(&src->i_mutex); } /* determine range to clone */ @@ -2563,6 +2568,12 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd, !IS_ALIGNED(destoff, bs)) goto out_unlock; + /* verify if ranges are overlapped within the same file */ + if (same_inode) { + if (destoff + len > off && destoff < off + len) + goto out_unlock; + } + if (destoff > inode->i_size) { ret = btrfs_cont_expand(inode, inode->i_size, destoff); if (ret) @@ -2839,7 +2850,8 @@ out: unlock_extent(&BTRFS_I(src)->io_tree, off, off + len - 1); out_unlock: mutex_unlock(&src->i_mutex); - mutex_unlock(&inode->i_mutex); + if (!same_inode) + mutex_unlock(&inode->i_mutex); vfree(buf); btrfs_free_path(path); out_fput: -- 1.7.7 -- 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 http://vger.kernel.org/majordomo-info.html
David Sterba
2013-Apr-15 15:13 UTC
Re: [PATCH v2] Btrfs: allow file data clone within a file
On Mon, Apr 15, 2013 at 10:55:45AM +0800, Liu Bo wrote:> @@ -2563,6 +2568,12 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd, > !IS_ALIGNED(destoff, bs)) > goto out_unlock; > > + /* verify if ranges are overlapped within the same file */ > + if (same_inode) { > + if (destoff + len > off && destoff < off + len) > + goto out_unlock;Although I find the condition hard to read, it''s correct. Reviewed-by: David Sterba <dsterba@suse.cz> -- 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 http://vger.kernel.org/majordomo-info.html