On Thu, Sep 28, 2017 at 01:54:26PM -0500, Goldwyn Rodrigues wrote:
> From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
>
> Partial writes are performed when there is an error midway
> while performing the I/O. Perform the write exactly once and
> return the number of bytes written.
>
> Signed-off-by: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
> ---
> io/io.h | 1 +
> io/pwrite.c | 25 ++++++++++++++++++++++++-
> man/man8/xfs_io.8 | 3 +++
> 3 files changed, 28 insertions(+), 1 deletion(-)
>
> diff --git a/io/io.h b/io/io.h
> index 2bc7ac4a..5875e85a 100644
> --- a/io/io.h
> +++ b/io/io.h
> @@ -24,6 +24,7 @@
> #define IO_RANDOM ( 0)
> #define IO_FORWARD ( 1)
> #define IO_BACKWARD (-1)
> +#define IO_PARTIAL (2)
I would name this CALL_ONCE instead of PARTIAL since we don't know
beforehand that the write will return partial results -- it could
succeed at writing the entire buffer.
--D
>
> /*
> * File descriptor options
> diff --git a/io/pwrite.c b/io/pwrite.c
> index 8289c3ee..40f537b3 100644
> --- a/io/pwrite.c
> +++ b/io/pwrite.c
> @@ -47,6 +47,7 @@ pwrite_help(void)
> " -W -- call fsync(2) at the end (included in timing results)\n"
> " -B -- write backwards through the range from offset (backwards N bytes)\n"
> " -F -- write forwards through the range of bytes from offset (default)\n"
> +" -P -- return Partial writes, perform one call and return bytes written\n"
> " -R -- write at random offsets in the specified range of bytes\n"
> " -Z N -- zeed the random number generator (used when writing randomly)\n"
> " (heh, zorry, the -s/-S arguments were already in use in pwrite)\n"
> @@ -255,6 +256,22 @@ write_buffer(
> return ops;
> }
>
> +static int
> +write_partial(
> + off64_t offset,
> + long long count,
> + long long *total,
> + int pwritev2_flags)
> +{
> + size_t bytes;
> + bytes = do_pwrite(file->fd, offset, count, count, pwritev2_flags);
> + if (bytes < 0)
> + return -1;
> + *total = bytes;
> + return 1;
> +}
> +
> +
> static int
> pwrite_f(
> int argc,
> @@ -276,7 +293,7 @@ pwrite_f(
> init_cvtnum(&fsblocksize, &fssectsize);
> bsize = fsblocksize;
>
> - while ((c = getopt(argc, argv, "b:BCdf:Fi:NqRs:S:uV:wWZ:")) != EOF) {
> + while ((c = getopt(argc, argv, "b:BCdf:Fi:NqRs:PS:uV:wWZ:")) != EOF) {
> switch (c) {
> case 'b':
> tmp = cvtnum(fsblocksize, fssectsize, optarg);
> @@ -298,6 +315,9 @@ pwrite_f(
> case 'R':
> direction = IO_RANDOM;
> break;
> + case 'P':
> + direction = IO_PARTIAL;
> + break;
> case 'd':
> dflag = 1;
> break;
> @@ -389,6 +409,9 @@ pwrite_f(
> case IO_BACKWARD:
> c = write_backward(offset, &count, &total, pwritev2_flags);
> break;
> + case IO_PARTIAL:
> + c = write_partial(offset, count, &total, pwritev2_flags);
> + break;
> default:
> total = 0;
> ASSERT(0);
> diff --git a/man/man8/xfs_io.8 b/man/man8/xfs_io.8
> index f410ce9a..b21a8145 100644
> --- a/man/man8/xfs_io.8
> +++ b/man/man8/xfs_io.8
> @@ -229,6 +229,9 @@ write the buffers in a reserve sequential direction.
> .B \-R
> write the buffers in the give range in a random order.
> .TP
> +.B \-P
> +return Partial writes, perform one call and return the bytes written.
> +.TP
> .B \-Z seed
> specify the random number seed used for random write
> .TP
> --
> 2.14.1
>
> --
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