[PATCH v21 24/30] xfs: Provide a splice-read stub

David Howells
2023-05-20T00:02:16Z

Provide a splice_read stub for XFS. This does a stat count and a shutdown
check before proceeding, then emits a new trace line and locks the inode
across the call to filemap_splice_read() and adds to the stats afterwards.
Splicing from direct I/O or DAX is handled by the caller.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Christoph Hellwig <hch@lst.de>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: Jens Axboe <axboe@kernel.dk>
cc: Darrick J. Wong <djwong@kernel.org>
cc: linux-xfs@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
cc: linux-block@vger.kernel.org
cc: linux-mm@kvack.org
---
fs/xfs/xfs_file.c | 30 +++++++++++++++++++++++++++++-
fs/xfs/xfs_trace.h | 2 +-
2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index aede746541f8..08d632668e94 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -306,6 +306,34 @@ xfs_file_read_iter(
return ret;
}

+STATIC ssize_t
+xfs_file_splice_read(
+ struct file *in,
+ loff_t *ppos,
+ struct pipe_inode_info *pipe,
+ size_t len,
+ unsigned int flags)
+{
+ struct inode *inode = file_inode(in);
+ struct xfs_inode *ip = XFS_I(inode);
+ struct xfs_mount *mp = ip->i_mount;
+ ssize_t ret = 0;
+
+ XFS_STATS_INC(mp, xs_read_calls);
+
+ if (xfs_is_shutdown(mp))
+ return -EIO;
+
+ trace_xfs_file_splice_read(ip, *ppos, len);
+
+ xfs_ilock(ip, XFS_IOLOCK_SHARED);
+ ret = filemap_splice_read(in, ppos, pipe, len, flags);
+ xfs_iunlock(ip, XFS_IOLOCK_SHARED);
+ if (ret > 0)
+ XFS_STATS_ADD(mp, xs_read_bytes, ret);
+ return ret;
+}
+
/*
* Common pre-write limit and setup checks.
*
@@ -1423,7 +1451,7 @@ const struct file_operations xfs_file_operations = {
.llseek = xfs_file_llseek,
.read_iter = xfs_file_read_iter,
.write_iter = xfs_file_write_iter,
- .splice_read = generic_file_splice_read,
+ .splice_read = xfs_file_splice_read,
.splice_write = iter_file_splice_write,
.iopoll = iocb_bio_iopoll,
.unlocked_ioctl = xfs_file_ioctl,
diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
index cd4ca5b1fcb0..4db669203149 100644
--- a/fs/xfs/xfs_trace.h
+++ b/fs/xfs/xfs_trace.h
@@ -1445,7 +1445,6 @@ DEFINE_RW_EVENT(xfs_file_direct_write);
DEFINE_RW_EVENT(xfs_file_dax_write);
DEFINE_RW_EVENT(xfs_reflink_bounce_dio_write);

-
DECLARE_EVENT_CLASS(xfs_imap_class,
TP_PROTO(struct xfs_inode *ip, xfs_off_t offset, ssize_t count,
int whichfork, struct xfs_bmbt_irec *irec),
@@ -1535,6 +1534,7 @@ DEFINE_SIMPLE_IO_EVENT(xfs_zero_eof);
DEFINE_SIMPLE_IO_EVENT(xfs_end_io_direct_write);
DEFINE_SIMPLE_IO_EVENT(xfs_end_io_direct_write_unwritten);
DEFINE_SIMPLE_IO_EVENT(xfs_end_io_direct_write_append);
+DEFINE_SIMPLE_IO_EVENT(xfs_file_splice_read);

DECLARE_EVENT_CLASS(xfs_itrunc_class,
TP_PROTO(struct xfs_inode *ip, xfs_fsize_t new_size),