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Tue, 14 Feb 2023 17:24:09 +0000 (UTC) From: Mezgani Ali Message-Id: <37F327B5-D7D9-4603-AF49-0B6B5AFD6FFC@icloud.com> Content-Type: multipart/alternative; boundary="Apple-Mail=_0D6780EF-1554-4011-80F3-BBC5188E67D7" Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3696.120.41.1.2\)) Subject: Re: [PATCH v14 08/17] splice: Do splice read from a file without using ITER_PIPE Date: Tue, 14 Feb 2023 18:24:02 +0100 In-Reply-To: <20230214171330.2722188-9-dhowells@redhat.com> Cc: Jens Axboe , Al Viro , Christoph Hellwig , Matthew Wilcox , Jan Kara , Jeff Layton , David Hildenbrand , Jason Gunthorpe , Logan Gunthorpe , Hillf Danton , linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Christoph Hellwig , John Hubbard , Mezgani Ali To: David Howells References: <20230214171330.2722188-1-dhowells@redhat.com> <20230214171330.2722188-9-dhowells@redhat.com> X-Mailer: Apple Mail (2.3696.120.41.1.2) X-Proofpoint-GUID: FqIhptYELt27WpqCuxL2caasZBvUrXwC X-Proofpoint-ORIG-GUID: FqIhptYELt27WpqCuxL2caasZBvUrXwC X-Proofpoint-Virus-Version: =?UTF-8?Q?vendor=3Dfsecure_engine=3D1.1.170-22c6f66c430a71ce266a39bfe25bc?= =?UTF-8?Q?2903e8d5c8f:6.0.138,18.0.572,17.0.605.474.0000000_definitions?= =?UTF-8?Q?=3D2020-02-14=5F11:2020-02-14=5F02,2020-02-14=5F11,2020-01-23?= =?UTF-8?Q?=5F02_signatures=3D0?= X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 mlxscore=0 phishscore=0 bulkscore=0 suspectscore=0 mlxlogscore=999 adultscore=0 malwarescore=0 clxscore=1011 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2209130000 definitions=main-2302140149 X-Rspamd-Queue-Id: 4440C80028 X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: nj8cmyze8g8s5mkze3dmmc7shm768npc X-HE-Tag: 1676395462-350240 X-HE-Meta: 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 9TK6ZVdf 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: --Apple-Mail=_0D6780EF-1554-4011-80F3-BBC5188E67D7 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii Hello Kernel, Whom made this bad quality of code : > - 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 =3D *ppos; > - ret =3D call_read_iter(in, &kiocb, &to); > - if (ret > 0) { > - *ppos =3D 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 =3D=3D -EFAULT) > - ret =3D -EAGAIN; > - } > - > - return ret; I pretend that keeping the file clear, clean and explicit far from new = comers is much more needed. Please a cache flush is wonderful here. Kind regards, -- Mezgani Ali SVP of Engineering https://www.nativelabs.ma/ ali.mezgani@nativelabs.ma +212 6 44 17 94 51 =20 > On 14/02/2023, at 18:13, David Howells wrote: >=20 > Make generic_file_splice_read() use filemap_splice_read() and > direct_splice_read() rather than using an ITER_PIPE and = call_read_iter(). >=20 > With this, ITER_PIPE is no longer used. >=20 > Signed-off-by: David Howells > cc: Jens Axboe > cc: Christoph Hellwig > cc: Al Viro > cc: David Hildenbrand > cc: John Hubbard > cc: linux-mm@kvack.org > cc: linux-block@vger.kernel.org > cc: linux-fsdevel@vger.kernel.org > --- >=20 > Notes: > ver #14) > - Split out filemap_splice_read() into a separate patch. >=20 > fs/splice.c | 30 +++++++----------------------- > 1 file changed, 7 insertions(+), 23 deletions(-) >=20 > diff --git a/fs/splice.c b/fs/splice.c > index 4c6332854b63..a93478338cec 100644 > --- a/fs/splice.c > +++ b/fs/splice.c > @@ -391,29 +391,13 @@ 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 =3D *ppos; > - ret =3D call_read_iter(in, &kiocb, &to); > - if (ret > 0) { > - *ppos =3D 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 =3D=3D -EFAULT) > - ret =3D -EAGAIN; > - } > - > - return ret; > + if (unlikely(*ppos >=3D 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); >=20 >=20 --Apple-Mail=_0D6780EF-1554-4011-80F3-BBC5188E67D7 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=us-ascii Hello= Kernel,

Whom made = this bad quality of code :

- 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 =3D *ppos;
- ret =3D = call_read_iter(in, &kiocb, &to);
- if (ret = > 0) {
- *ppos =3D 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 =3D=3D -EFAULT)
- = = = ret =3D -EAGAIN;
- }
-
- = return ret;

I = pretend that keeping the file clear, clean and explicit far from new = comers is much more needed.

Please a cache flush is wonderful here.


Kind regards,
--
Mezgani Ali
SVP of Engineering
https://www.nativelabs.ma/
ali.mezgani@nativelabs.ma
+212 6 44 17 94 51

 






On 14/02/2023, at 18:13, David Howells <dhowells@redhat.com>= wrote:

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

With this, ITER_PIPE = is no longer used.

Signed-off-by: David = Howells <dhowells@redhat.com>
cc: Jens Axboe = <axboe@kernel.dk>
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-fsdevel@vger.kernel.org
---

Notes:
   ver = #14)
   - Split out filemap_splice_read() = into a separate patch.

fs/splice.c | 30 = +++++++-----------------------
1 file changed, 7 = insertions(+), 23 deletions(-)

diff --git = a/fs/splice.c b/fs/splice.c
index = 4c6332854b63..a93478338cec 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -391,29 +391,13 @@ 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 =3D *ppos;
- ret =3D = call_read_iter(in, &kiocb, &to);
- if (ret = > 0) {
- *ppos =3D 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 =3D=3D -EFAULT)
- = = = ret =3D -EAGAIN;
- }
-
- = return ret;
+ if (unlikely(*ppos >=3D = 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);



= --Apple-Mail=_0D6780EF-1554-4011-80F3-BBC5188E67D7--