Date: Thu, 09 Dec 2010 17:27:19 -0800 From: Bakul Shah <bakul@bitblocks.com> To: Kirk McKusick <mckusick@mckusick.com> Cc: freebsd-fs@freebsd.org, pjd@freebsd.org, Oliver Fromme <olli@lurza.secnetix.de> Subject: Re: TRIM support for UFS? Message-ID: <20101210012720.0C30C5B94@mail.bitblocks.com> In-Reply-To: Your message of "Thu, 09 Dec 2010 16:57:18 PST." <201012100057.oBA0vIgT065481@chez.mckusick.com> References: <201012100057.oBA0vIgT065481@chez.mckusick.com>
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On Thu, 09 Dec 2010 16:57:18 PST Kirk McKusick <mckusick@mckusick.com> wrote: > > To: Kirk McKusick <mckusick@mckusick.com> > > cc: Kostik Belousov <kostikbel@gmail.com>, freebsd-fs@freebsd.org, > > pjd@freebsd.org, Oliver Fromme <olli@lurza.secnetix.de> > > Subject: Re: TRIM support for UFS? > > Date: Thu, 09 Dec 2010 16:37:48 -0800 > > From: Bakul Shah <bakul@bitblocks.com> > > X-ASK-Info: Message Queued (2010/12/09 16:37:54) > > X-ASK-Info: Confirmed by User (2010/12/09 16:39:17) > > > > Would be nice if something like ftrim(fd, offset, size) or > > trim(path, offsetm size) or TRIM file ioctl is added, to free > > up blocks undelying a given range in a file. ftruncate can > > delete blocks at the end but there is no facility to lose > > blocks in the middle. Mainly handy for virtual disks and > > databases (and would work nicely with SEEK_DATA, SEEK_HOLE). > > We have discussed adding such a system call over the years (actually > we called it `release' rather than `trim'). If such a call ever does > get added, any blocks that it actually manages to release will get > passed through to BIO_DELETE by the changes that Kostik is soon to > add to the system. That is why this seemed like a good time to mention this! Probably most of the logic for this can be borrowed from ftruncate().... Pawel mentions g_delete() but it seems a bit indirect.
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