On Fri, 2 Aug 2013, majianpeng wrote:
> cephfs . show_layout
> >layyout.data_pool: 0
> >layout.object_size: 4194304
> >layout.stripe_unit: 4194304
> >layout.stripe_count: 1
>
> TestA:
> >dd if=/dev/urandom of=test bs=1M count=2 oflag=direct
> >dd if=/dev/urandom of=test bs=1M count=2 seek=4 oflag=direct
> >dd if=test of=/dev/null bs=6M count=1 iflag=direct
> The messages from func striped_read are:
> ceph: file.c:350 : striped_read 0~6291456 (read 0) got 2097152 HITSTRIPE SHORT
> ceph: file.c:350 : striped_read 2097152~4194304 (read 2097152) got 0 HITSTRIPE SHORT
> ceph: file.c:381 : zero tail 4194304
> ceph: file.c:390 : striped_read returns 6291456
> The hole of file is from 2M--4M.But actualy it zero the last 4M include
> the last 2M area which isn't a hole.
> Using this patch, the messages are:
> ceph: file.c:350 : striped_read 0~6291456 (read 0) got 2097152 HITSTRIPE SHORT
> ceph: file.c:358 : zero gap 2097152 to 4194304
> ceph: file.c:350 : striped_read 4194304~2097152 (read 4194304) got 2097152
> ceph: file.c:384 : striped_read returns 6291456
>
> TestB:
> >echo majianpeng > test
> >dd if=test of=/dev/null bs=2M count=1 iflag=direct
> The messages are:
> ceph: file.c:350 : striped_read 0~6291456 (read 0) got 11 HITSTRIPE SHORT
> ceph: file.c:350 : striped_read 11~6291445 (read 11) got 0 HITSTRIPE SHORT
> ceph: file.c:390 : striped_read returns 11
> For this case,it did once more striped_read.It's no meaningless.
> Using this patch, the message are:
> ceph: file.c:350 : striped_read 0~6291456 (read 0) got 11 HITSTRIPE SHORT
> ceph: file.c:384 : striped_read returns 11
>
> Big thanks to Yan Zheng for the patch.
Thanks for working through this!
Do you mind putting the test into a simple .sh script (or whatever) that
verifies this is working properly (that the read returns the correct data)
on a file in the currenct directory? Then we can add this to the
collection of tests in ceph.git/qa/workunits. Probably writing the same
thing to $CWD/test and /tmp/test.$$ and running cmp to verify they match
is the simplest.
Thanks!
sage
>
> Signed-off-by: Jianpeng Ma <majianpeng@xxxxxxxxx>
> Reviewed-by: Yan, Zheng <zheng.z.yan@xxxxxxxxx>
> ---
> fs/ceph/file.c | 40 +++++++++++++++++-----------------------
> 1 file changed, 17 insertions(+), 23 deletions(-)
>
> diff --git a/fs/ceph/file.c b/fs/ceph/file.c
> index 2ddf061..3d8d14d 100644
> --- a/fs/ceph/file.c
> +++ b/fs/ceph/file.c
> @@ -349,44 +349,38 @@ more:
> dout("striped_read %llu~%u (read %u) got %d%s%s\n", pos, left, read,
> ret, hit_stripe ? " HITSTRIPE" : "", was_short ? " SHORT" : "");
>
> - if (ret > 0) {
> - int didpages = (page_align + ret) >> PAGE_CACHE_SHIFT;
> -
> - if (read < pos - off) {
> - dout(" zero gap %llu to %llu\n", off + read, pos);
> - ceph_zero_page_vector_range(page_align + read,
> - pos - off - read, pages);
> + if (ret >= 0) {
> + int didpages;
> + if (was_short && (pos + ret < inode->i_size)) {
> + u64 tmp = min(this_len - ret,
> + inode->i_size - pos - ret);
> + dout(" zero gap %llu to %llu\n",
> + pos + ret, pos + ret + tmp);
> + ceph_zero_page_vector_range(page_align + read + ret,
> + tmp, pages);
> + ret += tmp;
> }
> +
> + didpages = (page_align + ret) >> PAGE_CACHE_SHIFT;
> pos += ret;
> read = pos - off;
> left -= ret;
> page_pos += didpages;
> pages_left -= didpages;
>
> - /* hit stripe? */
> - if (left && hit_stripe)
> + /* hit stripe and need continue*/
> + if (left && hit_stripe && pos < inode->i_size)
> goto more;
> +
> }
>
> - if (was_short) {
> + if (ret >= 0) {
> + ret = read;
> /* did we bounce off eof? */
> if (pos + left > inode->i_size)
> *checkeof = 1;
> -
> - /* zero trailing bytes (inside i_size) */
> - if (left > 0 && pos < inode->i_size) {
> - if (pos + left > inode->i_size)
> - left = inode->i_size - pos;
> -
> - dout("zero tail %d\n", left);
> - ceph_zero_page_vector_range(page_align + read, left,
> - pages);
> - read += left;
> - }
> }
>
> - if (ret >= 0)
> - ret = read;
> dout("striped_read returns %d\n", ret);
> return ret;
> }
> --
> 1.8.1.2
>
>
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