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From: Theodore Ts'o <tytso-3s7WtUTddSA@public.gmane.org>
To: Linus Torvalds
	<torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
Cc: "Darrick J. Wong"
	<darrick.wong-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>,
	Jens Axboe <axboe-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org>,
	Christoph Hellwig <hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>,
	Andrew Morton
	<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
	"Martin K. Petersen"
	<martin.petersen-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>,
	Linux API <linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	Linux Kernel Mailing List
	<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	shane.seymour-ZPxbGqLxI0U@public.gmane.org,
	Bruce Fields <bfields-uC3wQj2KruNg9hUCZPvPmw@public.gmane.org>,
	linux-fsdevel
	<linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	Jeff Layton <jlayton-vpEMnDpepFuMZCB2o+C8xQ@public.gmane.org>
Subject: Re: [PATCH 2/2] block: create ioctl to discard-or-zeroout a range of blocks
Date: Thu, 3 Mar 2016 13:21:46 -0500	[thread overview]
Message-ID: <20160303182146.GG9772@thunk.org> (raw)
In-Reply-To: <CA+55aFwPA1X8XGTdVZmP5uzkWMwj+X=bjkGVcEkZDme+qskrzQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>

On Thu, Mar 03, 2016 at 09:55:38AM -0800, Linus Torvalds wrote:
> But that essentially says that we shouldn't expose this interface at
> all (unless we trust our white-lists - I'm sure they are getting
> better, but if nobody has ever really _relied_ on the zeroing behavior
> of trim, then I guess there could be tons of bugs lurking).

We don't, so this interface won't be useful for SATA disks, where
we'll need to write zeros until the SATA folks get off their duffs and
fix it with a new, reliable trim command.

But it will be useful for other storage systems, such as eMMC devices,
which *do* have a reliable trim command.  So it may be that the first
place we'll see widepspread usage of this will be in the low-end and
high-end systems (where we can rely on eMMC's reliable trim and SCSI's
WRITE SAME command).

But that's why we want to have a new interface which is distinct from
BLKDISCARD.  We want one interface for an advisory hint (we don't care
about the contents, so if it's convenient, feel free to forget about
the contents and replace it by zeros), and something where it truly is
a zeroout command.  The intention is that BLKZEROOUT will be the
reliable zeroout command, while BLKDISCARD will be the unreliable
advisory hint.

						- Ted

  parent reply	other threads:[~2016-03-03 18:21 UTC|newest]

Thread overview: 82+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-03-02  4:09 [PATCH v5.1 0/2] create BLKZEROOUT ioctl that invalidates page cache Darrick J. Wong
2016-03-02  4:09 ` [PATCH 1/2] block: invalidate the page cache when issuing BLKZEROOUT Darrick J. Wong
2016-03-02  9:19   ` Christoph Hellwig
2016-03-02  4:09 ` [PATCH 2/2] block: create ioctl to discard-or-zeroout a range of blocks Darrick J. Wong
2016-03-02  9:20   ` Christoph Hellwig
     [not found]   ` <20160302040947.16685.42926.stgit-PTl6brltDGh4DFYR7WNSRA@public.gmane.org>
2016-03-02 18:52     ` Linus Torvalds
2016-03-02 22:56       ` Darrick J. Wong
2016-03-02 23:49         ` Linus Torvalds
2016-03-03 17:02           ` Theodore Ts'o
     [not found]             ` <20160303170205.GD24012-AKGzg7BKzIDYtjvyW6yDsg@public.gmane.org>
2016-03-03 17:55               ` Linus Torvalds
     [not found]                 ` <CA+55aFwPA1X8XGTdVZmP5uzkWMwj+X=bjkGVcEkZDme+qskrzQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-03-03 18:00                   ` Christoph Hellwig
2016-03-03 18:14                   ` Martin K. Petersen
2016-03-03 18:21                   ` Theodore Ts'o [this message]
     [not found]           ` <CA+55aFyNPnjJ-Nsu3bMr+HuLQnkj1B8FMddNnXW7HJqxdUzJmQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-03-03 18:01             ` Martin K. Petersen
     [not found]               ` <yq1bn6v8mqg.fsf-+q57XtR/GgMb6DWv4sQWN6xOck334EZe@public.gmane.org>
2016-03-03 18:09                 ` Christoph Hellwig
     [not found]                   ` <20160303180924.GA4116-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2016-03-03 18:12                     ` Darrick J. Wong
2016-03-03 18:54                   ` Martin K. Petersen
     [not found]                     ` <yq1vb5375oh.fsf-+q57XtR/GgMb6DWv4sQWN6xOck334EZe@public.gmane.org>
2016-03-03 22:39                       ` Theodore Ts'o
     [not found]                         ` <20160303223952.GE24012-AKGzg7BKzIDYtjvyW6yDsg@public.gmane.org>
2016-03-03 23:10                           ` Dave Chinner
2016-03-04  0:20                             ` Theodore Ts'o
2016-03-09 22:20                             ` Gregory Farnum
2016-03-09 23:08                               ` Theodore Ts'o
2016-03-10 14:58                                 ` Ric Wheeler
     [not found]                                   ` <56E18B9B.5070503-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2016-03-10 18:33                                     ` Linus Torvalds
     [not found]                                       ` <CA+55aFyw1nN4ze3-AGGE27evOZuXnkJC9C-W5QRUR=zKHqObGg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-03-10 21:47                                         ` Theodore Ts'o
2016-03-11  4:42                                       ` Ric Wheeler
2016-03-11 13:59                                         ` One Thousand Gnomes
     [not found]                                           ` <20160311135952.57a44931-qBU/x9rampVanCEyBjwyrvXRex20P6io@public.gmane.org>
2016-03-11 15:27                                             ` Theodore Ts'o
2016-03-11 17:23                                           ` Linus Torvalds
     [not found]                                             ` <CA+55aFwX2GYYN53E9qaTym=gp1aRjSA5f1G+N5WEiRd1dOJhFA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-03-11 17:30                                               ` Andy Lutomirski
2016-03-11 18:25                                                 ` Linus Torvalds
     [not found]                                                   ` <CA+55aFxQOgDjL643J33d-3q7gYGvyN84vCn4qJq-Ox8E-WRx9w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-03-11 22:30                                                     ` Dave Chinner
2016-03-12  0:33                                                       ` Linus Torvalds
2016-03-12  0:35                                                       ` Theodore Ts'o
     [not found]                                                         ` <20160312003556.GF32214-AKGzg7BKzIDYtjvyW6yDsg@public.gmane.org>
2016-03-12  0:44                                                           ` Linus Torvalds
2016-03-12  7:19                                                             ` Theodore Ts'o
     [not found]                                                               ` <20160312071945.GA3419-AKGzg7BKzIDYtjvyW6yDsg@public.gmane.org>
2016-03-12 10:11                                                                 ` Thomas Schoebel-Theuer
2016-03-13 23:30                                                             ` Dave Chinner
2016-03-14 10:34                                                               ` Ric Wheeler
     [not found]                                                                 ` <56E69398.7030508-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-03-14 14:46                                                                   ` Theodore Ts'o
2016-03-15 20:14                                                                     ` Dave Chinner
2016-03-15 20:43                                                                       ` Linus Torvalds
     [not found]                                                                         ` <CA+55aFwHLJffmN-Dw=yZCGKzxe_2Tm9h2GjdaFL3JdvYXNstRw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-03-15 21:29                                                                           ` Theodore Ts'o
2016-03-15 22:33                                                                           ` Dave Chinner
2016-03-15 22:52                                                                             ` Theodore Ts'o
2016-03-16  1:51                                                                               ` Darrick J. Wong
     [not found]                                                                                 ` <20160316015139.GC5826-PTl6brltDGh4DFYR7WNSRA@public.gmane.org>
2016-03-16 21:45                                                                                   ` Andreas Dilger
     [not found]                                                                                     ` <7674C689-C07E-4D38-85EB-4FD9B55CBB35-m1MBpc4rdrD3fQ9qLvQP4Q@public.gmane.org>
2016-03-17  0:15                                                                                       ` Theodore Ts'o
     [not found]                                                                                         ` <20160317001502.GF23593-AKGzg7BKzIDYtjvyW6yDsg@public.gmane.org>
2016-03-17  0:33                                                                                           ` Eric Sandeen
2016-03-17  0:59                                                                                             ` Theodore Ts'o
     [not found]                                                                                             ` <56E9FB73.6040803-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-03-17  5:18                                                                                               ` Gregory Farnum
2016-03-17 12:36                                                                                                 ` Theodore Ts'o
     [not found]                                                                                                 ` <CAC6JEv-CGaphHj6hVXUhFS+Dc4jS46nO1yOfKF5yA8AnDwqgOw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-03-17 17:47                                                                                                   ` Linus Torvalds
2016-03-17 17:50                                                                                                     ` Ric Wheeler
2016-03-17 17:59                                                                                                       ` Linus Torvalds
2016-03-17 18:35                                                                                                     ` Chris Mason
     [not found]                                                                                                       ` <20160317183512.GA76233-HIXDwvFErZjFYCXBM6kdu7fOX0fSgVTm@public.gmane.org>
2016-03-17 20:49                                                                                                         ` Andreas Dilger
     [not found]                                                                                                           ` <819F38A3-51A7-4874-8314-8A6004495716-m1MBpc4rdrD3fQ9qLvQP4Q@public.gmane.org>
2016-03-17 21:00                                                                                                             ` Chris Mason
     [not found]                                                                                                               ` <20160317210018.GA78710-HIXDwvFErZjFYCXBM6kdu7fOX0fSgVTm@public.gmane.org>
2016-03-18  3:20                                                                                                                 ` Theodore Ts'o
     [not found]                                                                                                                   ` <20160318032023.GK23593-AKGzg7BKzIDYtjvyW6yDsg@public.gmane.org>
2016-03-18 15:15                                                                                                                     ` Jeff Moyer
     [not found]                                                                                                                       ` <x491t7795ro.fsf-RRHT56Q3PSP4kTEheFKJxxDDeQx5vsVwAInAS/Ez/D0@public.gmane.org>
2016-03-18 20:05                                                                                                                         ` Martin K. Petersen
     [not found]                                                                                                     ` <CA+55aFzbzXb9ApP5FnVZihWRpWGO1-YnJj_Giip5LfD6=uvf0w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-03-18  6:52                                                                                                       ` Gregory Farnum
     [not found]                                                                                                         ` <CAC6JEv-MuU2sWSvftjHhOhZsE2Fz49Ffv6cm1FMnju5egcyvmQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-03-18  7:19                                                                                                           ` Linus Torvalds
2016-03-17  1:01                                                                                   ` Dave Chinner
2016-03-17  2:38                                                                                     ` Darrick J. Wong
     [not found]                                                                               ` <20160315225224.GD23848-AKGzg7BKzIDYtjvyW6yDsg@public.gmane.org>
2016-03-18 22:55                                                                                 ` NeilBrown
2016-03-15 23:06                                                                             ` Linus Torvalds
     [not found]                                                                               ` <CA+55aFxCpza3_3J8kP9E0gLKHiSitZHjC4UMS_ZfZ_HBTC9=Bg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-03-15 23:14                                                                                 ` Linus Torvalds
     [not found]                                                                                   ` <CA+55aFw80NXB9L7ooxV0zr3oaf4zWzZAJcb87ib58n=toiCn7g-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-03-16  0:08                                                                                     ` Dave Chinner
2016-03-15 23:52                                                                               ` Dave Chinner
2016-03-16  0:06                                                                                 ` Linus Torvalds
     [not found]                                                                                   ` <CA+55aFxZ=feGd+QGdhCN28kjd2XJO3PCj9NBoJJZ5E8_WMJiMA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-03-16  0:30                                                                                     ` Eric Sandeen
     [not found]                                                                                       ` <56E8A916.8050702-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2016-03-16  0:51                                                                                         ` Chris Mason
     [not found]                                                                                           ` <20160316005117.GA34410-HIXDwvFErZjFYCXBM6kdu7fOX0fSgVTm@public.gmane.org>
2016-03-16 22:23                                                                                             ` Chris Mason
     [not found]                                                                                               ` <20160316222343.GA53649-HIXDwvFErZjFYCXBM6kdu7fOX0fSgVTm@public.gmane.org>
2016-03-17 13:49                                                                                                 ` Ric Wheeler
2016-03-15 22:38                                                                       ` Eric Sandeen
2016-03-03 22:56                     ` Dave Chinner
2016-03-04  2:30                       ` Thomas Schoebel-Theuer
2016-03-03 18:14                 ` Linus Torvalds
2016-03-02  9:15 ` [PATCH v5.1 0/2] create BLKZEROOUT ioctl that invalidates page cache Arnd Bergmann
2016-03-02  9:44   ` Christoph Hellwig
     [not found]     ` <20160302094416.GA16631-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2016-03-02 10:55       ` Arnd Bergmann

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