Re: Slow I/O on USB media after commit f664a3cc17b7d0a2bc3b3ab96181e1029b0ec0e6

[Andrea Vai <andrea.vai@unipv.it>]

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Il giorno ven, 27/09/2019 alle 17.47 +0200, Andrea Vai ha scritto:
> Il giorno mer, 25/09/2019 alle 21.36 +0200, Jens Axboe ha scritto:
> > On 9/25/19 9:30 PM, Alan Stern wrote:
> > [...]
> > > 
> > > I have attached the two patches to this email.  You should start
> > with a
> > > recent kernel source tree and apply the patches by doing:
> > > 
> > > 	git apply patch1 patch2
> > > 
> > > or something similar.  Then build a kernel from the new source
> > code and
> > > test it.
> > > 
> > > Ultimately, if nobody can find a way to restore the sequential
> I/O
> > > behavior we had prior to commit f664a3cc17b7, that commit may
> have
> > to
> > > be reverted.
> > 
> > Don't use patch1, it's buggy. patch2 should be enough to test the
> > theory.

As I didn't have any answer, I am quoting my last reply here:

> 
> Sorry, but if I cd into the "linux" directory and run the command
> 
> # git apply -v patch2
> 
> the result is that the patch cannot be applied correctly:
> 
> --------------------------------------------------------------------
> ----------
> Controllo della patch block/blk-mq.c in corso...
> error: durante la ricerca per:
> ?
> static blk_qc_t blk_mq_make_request(struct request_queue *q, struct
> bio *bio)?
> {?
> 	const int is_sync = op_is_sync(bio->bi_opf);?
> 	const int is_flush_fua = op_is_flush(bio->bi_opf);?
> 	struct blk_mq_alloc_data data = { .flags = 0};?
> 	struct request *rq;?
> 
> error: patch non riuscita: block/blk-mq.c:1931
> error: block/blk-mq.c: la patch non si applica correttamente
> --------------------------------------------------------------------
> ----------
> 
> The "linux" directory is the one generated by a fresh git clone:
> 
> git clone
> git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> 
> What am I doing wrong?
> 

Meanwhile, Alan tried to help me and gave me another patch (attached),
which doesn't work too, but gives a different error: "The git diff
header does not contain information about the file once removed 1
initial component of the path (row 14)" (actually, this is my
translation from the original message in Italian: "error:
l'intestazione git diff non riporta le informazioni sul file una volta
rimosso 1 componente iniziale del percorso (riga 14)")

I tested the two patches after a fresh git clone today, a few minutes
ago.

What can I do?

Thank you,
Bye
Andrea

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