This has been discussed in https://lore.kernel.org/linux-xfs/b2865bd6-2346-8f4d-168b-17f06bbedbed@xxxxxxxxx/ Here is Jens comment: From: Jens Axboe <axboe@xxxxxxxxx> To: "Darrick J. Wong" <djwong@xxxxxxxxxx>, fstests <fstests@xxxxxxxxxxxxxxx> Cc: io-uring@xxxxxxxxxxxxxxx, kernel-team@xxxxxx, linux-mm@xxxxxxxxx, linux-xfs@xxxxxxxxxxxxxxx, linux-fsdevel@xxxxxxxxxxxxxxx, david@xxxxxxxxxxxxx, jack@xxxxxxx, hch@xxxxxxxxxxxxx, willy@xxxxxxxxxxxxx, Stefan Roesch <shr@xxxxxx> Subject: Re: generic/471 regression with async buffered writes? Date: Thu, 18 Aug 2022 11:00:38 -0600 [thread overview] Message-ID: <b2865bd6-2346-8f4d-168b-17f06bbedbed@xxxxxxxxx> (raw) In-Reply-To: <Yv5quvRMZXlDXED/@magnolia> On 8/18/22 10:37 AM, Darrick J. Wong wrote: > Hi everyone, > > I noticed the following fstest failure on XFS on 6.0-rc1 that wasn't > there in 5.19: > > --- generic/471.out > +++ generic/471.out.bad > @@ -2,12 +2,10 @@ > pwrite: Resource temporarily unavailable > wrote 8388608/8388608 bytes at offset 0 > XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) > -RWF_NOWAIT time is within limits. > +pwrite: Resource temporarily unavailable > +(standard_in) 1: syntax error > +RWF_NOWAIT took seconds > 00000000: aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa ................ > * > -00200000: bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb bb ................ > -* > -00300000: aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa ................ > -* > read 8388608/8388608 bytes at offset 0 > XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) > > Is this related to the async buffered write changes, or should I keep > looking? AFAICT nobody else has mentioned problems with 471... The test is just broken. It made some odd assumptions on what RWF_NOWAIT means with buffered writes. There's been a discussion on it previously, I'll see if I can find the links. IIRC, the tldr is that the test doesn't really tie RWF_NOWAIT to whether we'll block or not. -- Jens Axboe On 1/12/23 8:55 PM, yangx.jy@xxxxxxxxxxx wrote: > !-------------------------------------------------------------------| > This Message Is From an External Sender > > |-------------------------------------------------------------------! > > Hi > > Kindly ping. ^_^ > > Best Regards, > Xiao Yang > > -----Original Message----- > From: Yang, Xiao/杨 晓 <yangx.jy@xxxxxxxxxxx> > Sent: 2022年11月17日 10:28 > To: Stefan Roesch <shr@xxxxxxxx>; shr@xxxxxx; djwong@xxxxxxxxxx > Cc: linux-xfs@xxxxxxxxxxxxxxx; Ruan, Shiyang/阮 世阳 <ruansy.fnst@xxxxxxxxxxx> > Subject: Re: [PATCH] xfs: Call kiocb_modified() for buffered write > > On 2022/11/17 3:00, Stefan Roesch write: >> >> On 11/16/22 6:42 AM, Xiao Yang wrote: >>> kiocb_modified() should be used for sync/async buffered write because >>> it will return -EAGAIN when IOCB_NOWAIT is set. Unfortunately, >>> kiocb_modified() is used by the common xfs_file_write_checks() which >>> is called by all types of write(i.e. buffered/direct/dax write). >>> This issue makes generic/471 with xfs always get the following error: >>> -------------------------------------------------------- >>> QA output created by 471 >>> pwrite: Resource temporarily unavailable wrote 8388608/8388608 bytes >>> at offset 0 XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX >>> ops/sec) >>> pwrite: Resource temporarily unavailable ... >>> -------------------------------------------------------- >>> >> There have been earlier discussions about this. Snippet from the >> earlier discussion: >> >> "generic/471 complains because it expects any write done with >> RWF_NOWAIT to succeed as long as the blocks for the write are already instantiated. >> This isn't necessarily a correct assumption, as there are other >> conditions that can cause an RWF_NOWAIT write to fail with -EAGAIN >> even if the range is already there." > > Hi Stefan, > > Thanks for your reply. > Could you give me the URL about the earlier discussions? > > kiocb_modified() makes all types of write always get -EAGAIN when RWF_NOWAIT is set. I don't think this patch[1] is correct because it changed the original logic. The original logic only makes buffered write get -EOPNOTSUPP when RWF_NOWAIT is set. > --------------------------------------------- > static int file_modified_flags(struct file *file, int flags) { ... > if (flags & IOCB_NOWAIT) > return -EAGAIN; > ... > } > int kiocb_modified(struct kiocb *iocb) > { > return file_modified_flags(iocb->ki_filp, iocb->ki_flags); } > --------------------------------------------- > PS: kiocb_modified() is used by the common xfs_file_write_checks() which is called by all types of write(i.e. buffered/direct/dax write). > >> >> So the test itself probably needs fixing. > > In my opinion, both kernel and the test probably need to be fixed. > > [1] 1aa91d9c9933 ("xfs: Add async buffered write support") > > Best Regards, > Xiao Yang
