From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Darrick J. Wong" Subject: Re: [PATCH 09/10] xfs: nowait aio support Date: Wed, 24 May 2017 09:49:58 -0700 Message-ID: <20170524164958.GU4519@birch.djwong.org> References: <20170524164150.9492-1-rgoldwyn@suse.de> <20170524164150.9492-10-rgoldwyn@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20170524164150.9492-10-rgoldwyn@suse.de> Sender: linux-block-owner@vger.kernel.org To: Goldwyn Rodrigues Cc: linux-fsdevel@vger.kernel.org, jack@suse.com, hch@infradead.org, linux-block@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org, axboe@kernel.dk, linux-api@vger.kernel.org, adam.manzanares@wdc.com, viro@zeniv.linux.org.uk, Goldwyn Rodrigues List-Id: linux-api@vger.kernel.org On Wed, May 24, 2017 at 11:41:49AM -0500, Goldwyn Rodrigues wrote: > From: Goldwyn Rodrigues > > 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. > > Signed-off-by: Goldwyn Rodrigues > Reviewed-by: Christoph Hellwig Looks good, Reviewed-by: Darrick J. Wong --D > --- > fs/xfs/xfs_file.c | 19 ++++++++++++++----- > fs/xfs/xfs_iomap.c | 17 +++++++++++++++++ > 2 files changed, 31 insertions(+), 5 deletions(-) > > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c > index 35703a801372..b307940e7d56 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..8b0e3c1e086d 100644 > --- a/fs/xfs/xfs_iomap.c > +++ b/fs/xfs/xfs_iomap.c > @@ -1016,6 +1016,15 @@ 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 +1042,14 @@ 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 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html