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Message-ID: <alpine.LFD.2.00.1402271249570.2247@localhost.localdomain> Date: Thu, 27 Feb 2014 12:56:54 +0100 (CET) From: Lukáš Czerner <lczerner@...hat.com> To: jon ernst <jonernst07@...il.com> cc: "linux-ext4@...r.kernel.org List" <linux-ext4@...r.kernel.org>, "Theodore Ts'o" <tytso@....edu>, linux-fsdevel@...r.kernel.org, xfs@....sgi.com Subject: Re: [PATCH 5/6 v2] ext4: Introduce FALLOC_FL_ZERO_RANGE flag for fallocate On Wed, 26 Feb 2014, jon ernst wrote: > Date: Wed, 26 Feb 2014 23:41:15 -0500 > From: jon ernst <jonernst07@...il.com> > To: Lukas Czerner <lczerner@...hat.com> > Cc: "linux-ext4@...r.kernel.org List" <linux-ext4@...r.kernel.org>, > Theodore Ts'o <tytso@....edu>, linux-fsdevel@...r.kernel.org, > xfs@....sgi.com > Subject: Re: [PATCH 5/6 v2] ext4: Introduce FALLOC_FL_ZERO_RANGE flag for > fallocate > > On Wed, Feb 26, 2014 at 1:00 AM, jon ernst <jonernst07@...il.com> wrote: > > On Tue, Feb 25, 2014 at 2:14 PM, Lukas Czerner <lczerner@...hat.com> wrote: > >> Introduce new FALLOC_FL_ZERO_RANGE flag for fallocate. This has the same > >> functionality as xfs ioctl XFS_IOC_ZERO_RANGE. > >> > >> It can be used to convert a range of file to zeros preferably without > >> issuing data IO. Blocks should be preallocated for the regions that span > >> holes in the file, and the entire range is preferable converted to > >> unwritten extents > >> > >> This can be also used to preallocate blocks past EOF in the same way as > >> with fallocate. Flag FALLOC_FL_KEEP_SIZE which should cause the inode > >> size to remain the same. > >> > >> Also add appropriate tracepoints. > >> > >> Signed-off-by: Lukas Czerner <lczerner@...hat.com> > >> --- > >> fs/ext4/ext4.h | 2 + > >> fs/ext4/extents.c | 270 +++++++++++++++++++++++++++++++++++++++++--- > >> fs/ext4/inode.c | 17 ++- > >> include/trace/events/ext4.h | 64 +++++------ > > >> static int > >> +ext4_ext_convert_initialized_extent(handle_t *handle, struct inode *inode, > >> + struct ext4_map_blocks *map, > >> + struct ext4_ext_path *path, int flags, > >> + unsigned int allocated, ext4_fsblk_t newblock) > >> +{ > >> + int ret = 0; > >> + int err = 0; > >> + > >> + /* > >> + * Make sure that the extent is no bigger than we support with > >> + * uninitialized extent > >> + */ > >> + if (map->m_len > EXT_UNINIT_MAX_LEN) > >> + map->m_len = EXT_UNINIT_MAX_LEN / 2; > > > Pardon my possible dumb question. Why do you use > "EXT_UNINIT_MAX_LEN/ 2;" here instead of "EXT_UNINIT_MAX_LEN" > I don't see the reason why we can't use EXT_UNINIT_MAX_LEN here. > > > (resend, Ping on this question, thank you!) Wow, that's an early ping :) I am sorry to disappoint you, my answer is not going to be that exciting :) Yes, we can just use EXT_UNINIT_MAX_LEN here. But EXT_UNINIT_MAX_LEN/2 would make it much more evenly spread out. I do not think there is any real world advantage to this and the behaviour should be the same in both cases. Thanks! -Lukas > > Thanks! > Jon > -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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