[PATCH v16 06/13] splice: Do splice read from a file without using ITER_PIPE

David Howells
2023-03-08T14:38:24Z

Make generic_file_splice_read() use filemap_splice_read() and
direct_splice_read() rather than using an ITER_PIPE and call_read_iter().

Make cifs use generic_file_splice_read() rather than doing it for itself.

Unexport filemap_splice_read().

With this, ITER_PIPE is no longer used.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jens Axboe <axboe@kernel.dk>
cc: Steve French <smfrench@gmail.com>
cc: Christoph Hellwig <hch@lst.de>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: David Hildenbrand <david@redhat.com>
cc: John Hubbard <jhubbard@nvidia.com>
cc: linux-mm@kvack.org
cc: linux-block@vger.kernel.org
cc: linux-cifs@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
---
fs/cifs/cifsfs.c | 8 ++++----
fs/cifs/cifsfs.h | 3 ---
fs/cifs/file.c | 16 ----------------
fs/splice.c | 30 +++++++-----------------------
mm/filemap.c | 1 -
5 files changed, 11 insertions(+), 47 deletions(-)

diff --git a/fs/cifs/cifsfs.c b/fs/cifs/cifsfs.c
index cbcf210d56e4..ba963a26cb19 100644
--- a/fs/cifs/cifsfs.c
+++ b/fs/cifs/cifsfs.c
@@ -1359,7 +1359,7 @@ const struct file_operations cifs_file_ops = {
.fsync = cifs_fsync,
.flush = cifs_flush,
.mmap = cifs_file_mmap,
- .splice_read = cifs_splice_read,
+ .splice_read = generic_file_splice_read,
.splice_write = iter_file_splice_write,
.llseek = cifs_llseek,
.unlocked_ioctl = cifs_ioctl,
@@ -1379,7 +1379,7 @@ const struct file_operations cifs_file_strict_ops = {
.fsync = cifs_strict_fsync,
.flush = cifs_flush,
.mmap = cifs_file_strict_mmap,
- .splice_read = cifs_splice_read,
+ .splice_read = generic_file_splice_read,
.splice_write = iter_file_splice_write,
.llseek = cifs_llseek,
.unlocked_ioctl = cifs_ioctl,
@@ -1417,7 +1417,7 @@ const struct file_operations cifs_file_nobrl_ops = {
.fsync = cifs_fsync,
.flush = cifs_flush,
.mmap = cifs_file_mmap,
- .splice_read = cifs_splice_read,
+ .splice_read = generic_file_splice_read,
.splice_write = iter_file_splice_write,
.llseek = cifs_llseek,
.unlocked_ioctl = cifs_ioctl,
@@ -1435,7 +1435,7 @@ const struct file_operations cifs_file_strict_nobrl_ops = {
.fsync = cifs_strict_fsync,
.flush = cifs_flush,
.mmap = cifs_file_strict_mmap,
- .splice_read = cifs_splice_read,
+ .splice_read = generic_file_splice_read,
.splice_write = iter_file_splice_write,
.llseek = cifs_llseek,
.unlocked_ioctl = cifs_ioctl,
diff --git a/fs/cifs/cifsfs.h b/fs/cifs/cifsfs.h
index 71fe0a0a7992..8b239854e590 100644
--- a/fs/cifs/cifsfs.h
+++ b/fs/cifs/cifsfs.h
@@ -100,9 +100,6 @@ extern ssize_t cifs_strict_readv(struct kiocb *iocb, struct iov_iter *to);
extern ssize_t cifs_user_writev(struct kiocb *iocb, struct iov_iter *from);
extern ssize_t cifs_direct_writev(struct kiocb *iocb, struct iov_iter *from);
extern ssize_t cifs_strict_writev(struct kiocb *iocb, struct iov_iter *from);
-extern ssize_t cifs_splice_read(struct file *in, loff_t *ppos,
- struct pipe_inode_info *pipe, size_t len,
- unsigned int flags);
extern int cifs_flock(struct file *pfile, int cmd, struct file_lock *plock);
extern int cifs_lock(struct file *, int, struct file_lock *);
extern int cifs_fsync(struct file *, loff_t, loff_t, int);
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 4d4a2d82636d..321f9b7c84c9 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -5066,19 +5066,3 @@ const struct address_space_operations cifs_addr_ops_smallbuf = {
.launder_folio = cifs_launder_folio,
.migrate_folio = filemap_migrate_folio,
};
-
-/*
- * Splice data from a file into a pipe.
- */
-ssize_t cifs_splice_read(struct file *in, loff_t *ppos,
- struct pipe_inode_info *pipe, size_t len,
- unsigned int flags)
-{
- if (unlikely(*ppos >= file_inode(in)->i_sb->s_maxbytes))
- return 0;
- if (unlikely(!len))
- return 0;
- if (in->f_flags & O_DIRECT)
- return direct_splice_read(in, ppos, pipe, len, flags);
- return filemap_splice_read(in, ppos, pipe, len, flags);
-}
diff --git a/fs/splice.c b/fs/splice.c
index abd21a455a2b..9c6adcd0a2e9 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -387,29 +387,13 @@ ssize_t generic_file_splice_read(struct file *in, loff_t *ppos,
struct pipe_inode_info *pipe, size_t len,
unsigned int flags)
{
- struct iov_iter to;
- struct kiocb kiocb;
- int ret;
-
- iov_iter_pipe(&to, ITER_DEST, pipe, len);
- init_sync_kiocb(&kiocb, in);
- kiocb.ki_pos = *ppos;
- ret = call_read_iter(in, &kiocb, &to);
- if (ret > 0) {
- *ppos = kiocb.ki_pos;
- file_accessed(in);
- } else if (ret < 0) {
- /* free what was emitted */
- pipe_discard_from(pipe, to.start_head);
- /*
- * callers of ->splice_read() expect -EAGAIN on
- * "can't put anything in there", rather than -EFAULT.
- */
- if (ret == -EFAULT)
- ret = -EAGAIN;
- }
-
- return ret;
+ if (unlikely(*ppos >= file_inode(in)->i_sb->s_maxbytes))
+ return 0;
+ if (unlikely(!len))
+ return 0;
+ if (in->f_flags & O_DIRECT)
+ return direct_splice_read(in, ppos, pipe, len, flags);
+ return filemap_splice_read(in, ppos, pipe, len, flags);
}
EXPORT_SYMBOL(generic_file_splice_read);

diff --git a/mm/filemap.c b/mm/filemap.c
index 2723104cc06a..3a93515ae2ed 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2967,7 +2967,6 @@ ssize_t filemap_splice_read(struct file *in, loff_t *ppos,

return total_spliced ? total_spliced : error;
}
-EXPORT_SYMBOL(filemap_splice_read);

static inline loff_t folio_seek_hole_data(struct xa_state *xas,
struct address_space *mapping, struct folio *folio,