From 1364b1d4b5df31a05b6a3e6fdeb5371dbd4bd8ac Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Thu, 18 Jan 2018 13:55:20 -0800 Subject: [PATCH] xfs: reflink should break pnfs leases before sharing blocks Before we share blocks between files, we need to break the pnfs leases on the layout before we start slicing and dicing the block map. The structure of this function sets us up for the lock contention reduction in the next patch. Signed-off-by: Darrick J. Wong Reviewed-by: Brian Foster Reviewed-by: Christoph Hellwig --- fs/xfs/xfs_reflink.c | 48 +++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 47 insertions(+), 1 deletion(-) diff --git a/fs/xfs/xfs_reflink.c b/fs/xfs/xfs_reflink.c index bcc2ad4f0899..bac464f0bc59 100644 --- a/fs/xfs/xfs_reflink.c +++ b/fs/xfs/xfs_reflink.c @@ -1244,6 +1244,50 @@ err: return error; } +/* + * Grab the exclusive iolock for a data copy from src to dest, making + * sure to abide vfs locking order (lowest pointer value goes first) and + * breaking the pnfs layout leases on dest before proceeding. The loop + * is needed because we cannot call the blocking break_layout() with the + * src iolock held, and therefore have to back out both locks. + */ +static int +xfs_iolock_two_inodes_and_break_layout( + struct inode *src, + struct inode *dest) +{ + int error; + +retry: + if (src < dest) { + inode_lock(src); + inode_lock_nested(dest, I_MUTEX_NONDIR2); + } else { + /* src >= dest */ + inode_lock(dest); + } + + error = break_layout(dest, false); + if (error == -EWOULDBLOCK) { + inode_unlock(dest); + if (src < dest) + inode_unlock(src); + error = break_layout(dest, true); + if (error) + return error; + goto retry; + } + if (error) { + inode_unlock(dest); + if (src < dest) + inode_unlock(src); + return error; + } + if (src > dest) + inode_lock_nested(src, I_MUTEX_NONDIR2); + return 0; +} + /* * Link a range of blocks from one file to another. */ @@ -1274,7 +1318,9 @@ xfs_reflink_remap_range( return -EIO; /* Lock both files against IO */ - lock_two_nondirectories(inode_in, inode_out); + ret = xfs_iolock_two_inodes_and_break_layout(inode_in, inode_out); + if (ret) + return ret; if (same_inode) xfs_ilock(src, XFS_MMAPLOCK_EXCL); else