From e2aaee9cd34d8396a48abf0b1be81a464c1d51c5 Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Mon, 29 Jun 2020 14:47:20 -0700 Subject: xfs: move helpers that lock and unlock two inodes against userspace IO Move the double-inode locking helpers to xfs_inode.c since they're not specific to reflink. Signed-off-by: Darrick J. Wong Reviewed-by: Brian Foster --- fs/xfs/xfs_inode.c | 93 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 93 insertions(+) (limited to 'fs/xfs/xfs_inode.c') diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c index 9aea7d68d8ab..24edec472a7c 100644 --- a/fs/xfs/xfs_inode.c +++ b/fs/xfs/xfs_inode.c @@ -3881,3 +3881,96 @@ xfs_log_force_inode( return 0; return xfs_log_force_lsn(ip->i_mount, lsn, XFS_LOG_SYNC, NULL); } + +/* + * 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 + * layout leases before proceeding. The loop is needed because we cannot call + * the blocking break_layout() with the iolocks 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; + + if (src > dest) + swap(src, dest); + +retry: + /* Wait to break both inodes' layouts before we start locking. */ + error = break_layout(src, true); + if (error) + return error; + if (src != dest) { + error = break_layout(dest, true); + if (error) + return error; + } + + /* Lock one inode and make sure nobody got in and leased it. */ + inode_lock(src); + error = break_layout(src, false); + if (error) { + inode_unlock(src); + if (error == -EWOULDBLOCK) + goto retry; + return error; + } + + if (src == dest) + return 0; + + /* Lock the other inode and make sure nobody got in and leased it. */ + inode_lock_nested(dest, I_MUTEX_NONDIR2); + error = break_layout(dest, false); + if (error) { + inode_unlock(src); + inode_unlock(dest); + if (error == -EWOULDBLOCK) + goto retry; + return error; + } + + return 0; +} + +/* + * Lock two inodes so that userspace cannot initiate I/O via file syscalls or + * mmap activity. + */ +int +xfs_ilock2_io_mmap( + struct xfs_inode *ip1, + struct xfs_inode *ip2) +{ + int ret; + + ret = xfs_iolock_two_inodes_and_break_layout(VFS_I(ip1), VFS_I(ip2)); + if (ret) + return ret; + if (ip1 == ip2) + xfs_ilock(ip1, XFS_MMAPLOCK_EXCL); + else + xfs_lock_two_inodes(ip1, XFS_MMAPLOCK_EXCL, + ip2, XFS_MMAPLOCK_EXCL); + return 0; +} + +/* Unlock both inodes to allow IO and mmap activity. */ +void +xfs_iunlock2_io_mmap( + struct xfs_inode *ip1, + struct xfs_inode *ip2) +{ + bool same_inode = (ip1 == ip2); + + xfs_iunlock(ip2, XFS_MMAPLOCK_EXCL); + if (!same_inode) + xfs_iunlock(ip1, XFS_MMAPLOCK_EXCL); + inode_unlock(VFS_I(ip2)); + if (!same_inode) + inode_unlock(VFS_I(ip1)); +} -- cgit v1.2.3