Re: [PATCH v3] manpage: update FALLOC_FL_INSERT_RANGE flag in fallocate

Michael Kerrisk (man-pages)
2015-05-08T09:40:26Z

Hi Namjae,

> Update FALLOC_FL_INSERT_RANGE flag in fallocate.

Sorry -- I should have said that I already applied your V2
patch and made the fix we discussed (and that you add below).
I just hadn't pushed to Git yet. Done now.

Cheers,

Michael

On 05/08/2015 07:28 AM, Namjae Jeon wrote:
> Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
> Signed-off-by: Ashish Sangwan <a.sangwan@samsung.com>
> ---
> man2/fallocate.2 | 89 ++++++++++++++++++++++++++++++++++++++++++++++++++++----
> 1 file changed, 84 insertions(+), 5 deletions(-)
>
> diff --git a/man2/fallocate.2 b/man2/fallocate.2
> index 0cc1a00..0d31027 100644
> --- a/man2/fallocate.2
> +++ b/man2/fallocate.2
> @@ -228,6 +228,59 @@ ext4, for extent-based files (since Linux 3.15)
> .IP *
> SMB3 (since Linux 3.17)
> .\" commit 30175628bf7f521e9ee31ac98fa6d6fe7441a556
> +.SS Increasing file space
> +flag (available since Linux 4.1)
> +.\" commit dd46c787788d5bf5b974729d43e4c405814a4c7d
> +Specifying the
> +.BR FALLOC_FL_INSERT_RANGE
> +flag in
> +.I mode
> +will increase the file space by inserting a hole within the file size without
> +overwriting any existing data.
> +The hole will start at
> +.I offset
> +and continue for
> +.I len
> +bytes.
> +For inserting hole inside file, the contents of the file starting at
> +.I offset
> +will be shifted towards right by
> +.I len
> +bytes.
> +Inserting a hole inside the file will increase the file size by
> +.I len
> +bytes.
> +
> +This mode has the same limitation as
> +.BR FALLOC_FL_COLLAPSE_RANGE
> +regarding the
> +granularity of the operation.
> +If the granularity requirements are not met,
> +.BR fallocate ()
> +will fail with the error
> +.BR EINVAL.
> +If the
> +.I offset
> +is greater than or equal to the end of file, an error is
> +returned.
> +For such type of operations, i.e. inserting a hole at the end of file,
> +.BR ftruncate(2)
> +should be used.
> +In case
> +.IR offset + len
> +exceeds the maximum file size, errno will be set to
> +.B EFBIG.
> +
> +No other flags may be specified in
> +.IR mode
> +in conjunction with
> +.BR FALLOC_FL_INSERT_RANGE .
> +
> +As of Linux 4.1,
> +.B FALLOC_FL_INSERT_RANGE
> +is supported by
> +XFS.
> +.\" commit a904b1ca5751faf5ece8600e18cd3b674afcca1b
> .SH RETURN VALUE
> On success,
> .BR fallocate ()
> @@ -245,6 +298,12 @@ is not a valid file descriptor, or is not opened for writing.
> .IR offset + len
> exceeds the maximum file size.
> .TP
> +.B EFBIG
> +.I mode
> +is
> +.BR FALLOC_FL_INSERT_RANGE ,
> +the current file size+len exceeds the maximum file size.
> +.TP
> .B EINTR
> A signal was caught during execution.
> .TP
> @@ -273,7 +332,17 @@ reaches or passes the end of the file.
> .B EINVAL
> .I mode
> is
> -.BR FALLOC_FL_COLLAPSE_RANGE ,
> +.BR FALLOC_FL_INSERT_RANGE
> +and the range specified by
> +.I offset
> +reaches or passes the end of the file.
> +.TP
> +.B EINVAL
> +.I mode
> +is
> +.BR FALLOC_FL_COLLAPSE_RANGE
> +or
> +.BR FALLOC_FL_INSERT_RANGE ,
> but either
> .I offset
> or
> @@ -282,18 +351,24 @@ is not a multiple of the filesystem block size.
> .TP
> .B EINVAL
> .I mode
> -contains both
> +contains either of
> .B FALLOC_FL_COLLAPSE_RANGE
> +or
> +.B FALLOC_FL_INSERT_RANGE
> and other flags;
> no other flags are permitted with
> -.BR FALLOC_FL_COLLAPSE_RANGE .
> +.BR FALLOC_FL_COLLAPSE_RANGE
> +or
> +.BR FALLOC_FL_INSERT_RANGE .
> .TP
> .B EINVAL
> .I mode
> is
> .BR FALLOC_FL_COLLAPSE_RANGE
> or
> -.BR FALLOC_FL_ZERO_RANGE ,
> +.BR FALLOC_FL_ZERO_RANGE
> +or
> +.BR FALLOC_FL_INSERT_RANGE ,
> but the file referred to by
> .I fd
> is not a regular file.
> @@ -345,6 +420,8 @@ specifies
> .BR FALLOC_FL_PUNCH_HOLE
> or
> .BR FALLOC_FL_COLLAPSE_RANGE
> +or
> +.BR FALLOC_FL_INSERT_RANGE
> and
> the file referred to by
> .I fd
> @@ -363,7 +440,9 @@ refers to a pipe or FIFO.
> .B ETXTBSY
> .I mode
> specifies
> -.BR FALLOC_FL_COLLAPSE_RANGE ,
> +.BR FALLOC_FL_COLLAPSE_RANGE
> +or
> +.BR FALLOC_FL_INSERT_RANGE ,
> but the file referred to by
> .IR fd
> is currently being executed.
>

--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/