LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Andres Freund <andres@anarazel.de>
To: Jeff Layton <jlayton@redhat.com>
Cc: David Howells <dhowells@redhat.com>,
	torvalds@linux-foundation.org, viro@zeniv.linux.org.uk,
	Theodore Ts'o <tytso@mit.edu>,
	Stefan Metzmacher <metze@samba.org>,
	Andreas Dilger <adilger.kernel@dilger.ca>,
	linux-ext4@vger.kernel.org, Aleksa Sarai <cyphar@cyphar.com>,
	Trond Myklebust <trond.myklebust@hammerspace.com>,
	Anna Schumaker <anna.schumaker@netapp.com>,
	linux-nfs@vger.kernel.org, linux-api@vger.kernel.org,
	raven@themaw.net, mszeredi@redhat.com, christian@brauner.io,
	jannh@google.com, darrick.wong@oracle.com, kzak@redhat.com,
	linux-fsdevel@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 00/14] VFS: Filesystem information [ver #18]
Date: Mon, 9 Mar 2020 12:22:40 -0700	[thread overview]
Message-ID: <20200309192240.nqf5bxylptw7mdm3@alap3.anarazel.de> (raw)
In-Reply-To: <2d31e2658e5f6651dc7d9908c4c12b6ba461fc88.camel@redhat.com>

Hi,

On 2020-03-09 13:50:59 -0400, Jeff Layton wrote:
> The PostgreSQL devs asked a while back for some way to tell whether
> there have been any writeback errors on a superblock w/o having to do
> any sort of flush -- just "have there been any so far".

Indeed.


> I sent a patch a few weeks ago to make syncfs() return errors when there
> have been writeback errors on the superblock. It's not merged yet, but
> once we have something like that in place, we could expose info from the
> errseq_t to userland using this interface.

I'm still a bit worried about the details of errseq_t being exposed to
userland. Partially because it seems to restrict further evolution of
errseq_t, and partially because it will likely up with userland trying
to understand it (it's e.g. just too attractive to report a count of
errors etc).

Is there a reason to not instead report a 64bit counter instead of the
cookie? In contrast to the struct file case we'd only have the space
overhead once per superblock, rather than once per #files * #fd. And it
seems that the maintenance of that counter could be done without
widespread changes, e.g. instead/in addition to your change:

> diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
> index ccb14b6a16b5..897439475315 100644
> --- a/include/linux/pagemap.h
> +++ b/include/linux/pagemap.h
> @@ -51,7 +51,10 @@ static inline void mapping_set_error(struct address_space *mapping, int error)
>  		return;
>
>  	/* Record in wb_err for checkers using errseq_t based tracking */
> -	filemap_set_wb_err(mapping, error);
> +	__filemap_set_wb_err(mapping, error);
> +
> +	/* Record it in superblock */
> +	errseq_set(&mapping->host->i_sb->s_wb_err, error);
>
>  	/* Record it in flags for now, for legacy callers */
>  	if (error == -ENOSPC)

Btw, seems like mapping_set_error() should have a non-inline cold path?

Greetings,

Andres Freund

  reply	other threads:[~2020-03-09 19:22 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-09 14:00 David Howells
2020-03-09 14:00 ` [PATCH 01/14] VFS: Add additional RESOLVE_* flags " David Howells
2020-03-09 20:56   ` Stefan Metzmacher
2020-03-09 21:13   ` David Howells
2020-03-10  0:55   ` Aleksa Sarai
2020-03-10  1:14     ` Linus Torvalds
2020-03-10  7:25     ` David Howells
2020-03-11 17:59       ` Linus Torvalds
2020-03-12  9:08         ` Stefan Metzmacher
2020-03-12 16:24           ` Linus Torvalds
2020-03-12 17:11             ` Stefan Metzmacher
2020-03-12 19:37               ` Al Viro
2020-03-12 21:48               ` Jeremy Allison
2020-03-13  9:59               ` Aleksa Sarai
2020-03-13 10:00                 ` Aleksa Sarai
2020-03-13 16:48                 ` Jeremy Allison
2020-03-13 18:28                 ` Al Viro
2020-03-13 18:35                   ` Jeremy Allison
2020-03-16 14:21                   ` Aleksa Sarai
2020-03-16 14:20                     ` Aleksa Sarai
2020-03-12 19:25             ` Al Viro
2020-03-12 16:56           ` David Howells
2020-03-12 18:09             ` Linus Torvalds
2020-03-13  9:53               ` Aleksa Sarai
2020-03-13  9:50         ` Aleksa Sarai
2020-03-09 14:01 ` [PATCH 02/14] fsinfo: Add fsinfo() syscall to query filesystem information " David Howells
2020-03-10  9:31   ` Christian Brauner
2020-03-10  9:32     ` [PATCH v19 01/14] fsinfo: Add fsinfo() syscall to query filesystem information Christian Brauner
2020-03-10  9:32       ` [PATCH v19 14/14] arch: wire up fsinfo syscall Christian Brauner
2020-03-09 14:01 ` [PATCH 03/14] fsinfo: Provide a bitmap of supported features [ver #18] David Howells
2020-03-09 14:01 ` [PATCH 04/14] fsinfo: Allow retrieval of superblock devname, options and stats " David Howells
2020-03-09 14:01 ` [PATCH 05/14] fsinfo: Allow fsinfo() to look up a mount object by ID " David Howells
2020-03-09 14:01 ` [PATCH 06/14] fsinfo: Add a uniquifier ID to struct mount " David Howells
2020-03-09 14:01 ` [PATCH 07/14] fsinfo: Allow mount information to be queried " David Howells
2020-03-10  9:04   ` Miklos Szeredi
2020-03-09 14:02 ` [PATCH 08/14] fsinfo: Allow the mount topology propogation flags to be retrieved " David Howells
2020-03-10  8:42   ` Christian Brauner
2020-03-09 14:02 ` [PATCH 09/14] fsinfo: Provide notification overrun handling support " David Howells
2020-03-09 14:02 ` [PATCH 10/14] fsinfo: sample: Mount listing program " David Howells
2020-03-09 14:02 ` [PATCH 11/14] fsinfo: Add API documentation " David Howells
2020-03-09 14:02 ` [PATCH 12/14] fsinfo: Add support for AFS " David Howells
2020-03-09 14:02 ` [PATCH 13/14] fsinfo: Example support for Ext4 " David Howells
2020-03-09 14:02 ` [PATCH 14/14] fsinfo: Example support for NFS " David Howells
2020-03-09 17:50 ` [PATCH 00/14] VFS: Filesystem information " Jeff Layton
2020-03-09 19:22   ` Andres Freund [this message]
2020-03-09 22:49     ` Jeff Layton
2020-03-10  0:18       ` Andres Freund
2020-03-09 20:02 ` Miklos Szeredi
2020-03-09 22:52 ` David Howells
2020-03-10  9:18   ` Miklos Szeredi

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200309192240.nqf5bxylptw7mdm3@alap3.anarazel.de \
    --to=andres@anarazel.de \
    --cc=adilger.kernel@dilger.ca \
    --cc=anna.schumaker@netapp.com \
    --cc=christian@brauner.io \
    --cc=cyphar@cyphar.com \
    --cc=darrick.wong@oracle.com \
    --cc=dhowells@redhat.com \
    --cc=jannh@google.com \
    --cc=jlayton@redhat.com \
    --cc=kzak@redhat.com \
    --cc=linux-api@vger.kernel.org \
    --cc=linux-ext4@vger.kernel.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-nfs@vger.kernel.org \
    --cc=linux-security-module@vger.kernel.org \
    --cc=metze@samba.org \
    --cc=mszeredi@redhat.com \
    --cc=raven@themaw.net \
    --cc=torvalds@linux-foundation.org \
    --cc=trond.myklebust@hammerspace.com \
    --cc=tytso@mit.edu \
    --cc=viro@zeniv.linux.org.uk \
    --subject='Re: [PATCH 00/14] VFS: Filesystem information [ver #18]' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).