From: Goldwyn Rodrigues <rgold...@suse.com> If IOCB_NOWAIT is set, bail if the i_rwsem is not lockable immediately.
IF IOMAP_NOWAIT is set, return EAGAIN in xfs_file_iomap_begin if it needs allocation either due to file extension, writing to a hole, or COW or waiting for other DIOs to finish. Return -EAGAIN if we don't have extent list in memory. Signed-off-by: Goldwyn Rodrigues <rgold...@suse.com> Reviewed-by: Christoph Hellwig <h...@lst.de> Reviewed-by: Darrick J. Wong <darrick.w...@oracle.com> --- fs/xfs/xfs_file.c | 19 ++++++++++++++----- fs/xfs/xfs_iomap.c | 22 ++++++++++++++++++++++ 2 files changed, 36 insertions(+), 5 deletions(-) diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c index 5fb5a0958a14..f87a8a66e6f7 100644 --- a/fs/xfs/xfs_file.c +++ b/fs/xfs/xfs_file.c @@ -541,8 +541,11 @@ xfs_file_dio_aio_write( iolock = XFS_IOLOCK_SHARED; } - xfs_ilock(ip, iolock); - + if (!xfs_ilock_nowait(ip, iolock)) { + if (iocb->ki_flags & IOCB_NOWAIT) + return -EAGAIN; + xfs_ilock(ip, iolock); + } ret = xfs_file_aio_write_checks(iocb, from, &iolock); if (ret) goto out; @@ -553,9 +556,15 @@ xfs_file_dio_aio_write( * otherwise demote the lock if we had to take the exclusive lock * for other reasons in xfs_file_aio_write_checks. */ - if (unaligned_io) - inode_dio_wait(inode); - else if (iolock == XFS_IOLOCK_EXCL) { + if (unaligned_io) { + /* If we are going to wait for other DIO to finish, bail */ + if (iocb->ki_flags & IOCB_NOWAIT) { + if (atomic_read(&inode->i_dio_count)) + return -EAGAIN; + } else { + inode_dio_wait(inode); + } + } else if (iolock == XFS_IOLOCK_EXCL) { xfs_ilock_demote(ip, XFS_IOLOCK_EXCL); iolock = XFS_IOLOCK_SHARED; } diff --git a/fs/xfs/xfs_iomap.c b/fs/xfs/xfs_iomap.c index 94e5bdf7304c..05dc87e8c1f5 100644 --- a/fs/xfs/xfs_iomap.c +++ b/fs/xfs/xfs_iomap.c @@ -995,6 +995,11 @@ xfs_file_iomap_begin( lockmode = xfs_ilock_data_map_shared(ip); } + if ((flags & IOMAP_NOWAIT) && !(ip->i_df.if_flags & XFS_IFEXTENTS)) { + error = -EAGAIN; + goto out_unlock; + } + ASSERT(offset <= mp->m_super->s_maxbytes); if ((xfs_fsize_t)offset + length > mp->m_super->s_maxbytes) length = mp->m_super->s_maxbytes - offset; @@ -1016,6 +1021,15 @@ xfs_file_iomap_begin( if ((flags & (IOMAP_WRITE | IOMAP_ZERO)) && xfs_is_reflink_inode(ip)) { if (flags & IOMAP_DIRECT) { + /* + * A reflinked inode will result in CoW alloc. + * FIXME: It could still overwrite on unshared extents + * and not need allocation. + */ + if (flags & IOMAP_NOWAIT) { + error = -EAGAIN; + goto out_unlock; + } /* may drop and re-acquire the ilock */ error = xfs_reflink_allocate_cow(ip, &imap, &shared, &lockmode); @@ -1033,6 +1047,14 @@ xfs_file_iomap_begin( if ((flags & IOMAP_WRITE) && imap_needs_alloc(inode, &imap, nimaps)) { /* + * If nowait is set bail since we are going to make + * allocations. + */ + if (flags & IOMAP_NOWAIT) { + error = -EAGAIN; + goto out_unlock; + } + /* * We cap the maximum length we map here to MAX_WRITEBACK_PAGES * pages to keep the chunks of work done where somewhat symmetric * with the work writeback does. This is a completely arbitrary -- 2.12.0