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authorGoldwyn Rodrigues <rgoldwyn@suse.com>2017-06-20 07:05:48 -0500
committerJens Axboe <axboe@kernel.dk>2017-06-20 07:12:03 -0600
commit29a5d29ec181ebdc98a26cedbd76ce9870248892 (patch)
treef844c49eb8f2d04675e387dcef0e03fb9ca508c7
parent728fbc0e10b7f3ce2ee043b32e3453fd5201c055 (diff)
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xfs: nowait aio support
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 <rgoldwyn@suse.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
-rw-r--r--fs/xfs/xfs_file.c32
-rw-r--r--fs/xfs/xfs_iomap.c22
2 files changed, 48 insertions, 6 deletions
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 5fb5a0958a14..17f27a2fb5e2 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -237,7 +237,11 @@ xfs_file_dax_read(
if (!count)
return 0; /* skip atime */
- xfs_ilock(ip, XFS_IOLOCK_SHARED);
+ if (!xfs_ilock_nowait(ip, XFS_IOLOCK_SHARED)) {
+ if (iocb->ki_flags & IOCB_NOWAIT)
+ return -EAGAIN;
+ xfs_ilock(ip, XFS_IOLOCK_SHARED);
+ }
ret = dax_iomap_rw(iocb, to, &xfs_iomap_ops);
xfs_iunlock(ip, XFS_IOLOCK_SHARED);
@@ -541,7 +545,11 @@ 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)
@@ -553,9 +561,15 @@ 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;
}
@@ -585,7 +599,12 @@ xfs_file_dax_write(
size_t count;
loff_t pos;
- 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;
@@ -892,6 +911,7 @@ xfs_file_open(
return -EFBIG;
if (XFS_FORCED_SHUTDOWN(XFS_M(inode->i_sb)))
return -EIO;
+ file->f_mode |= FMODE_AIO_NOWAIT;
return 0;
}
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