This is a note to let you know that I've just added the patch titled
ceph: fix bugs about handling short-read for sync read mode.
to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ceph-fix-bugs-about-handling-short-read-for-sync-read-mode.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 02ae66d8b229708fd94b764f6c17ead1c7741fcf Mon Sep 17 00:00:00 2001
From: majianpeng <[email protected]>
Date: Tue, 6 Aug 2013 16:20:38 +0800
Subject: ceph: fix bugs about handling short-read for sync read mode.
From: majianpeng <[email protected]>
commit 02ae66d8b229708fd94b764f6c17ead1c7741fcf upstream.
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.
Reviewed-by: Yan, Zheng <[email protected]>
Signed-off-by: Jianpeng Ma <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
fs/ceph/file.c | 39 ++++++++++++++++-----------------------
1 file changed, 16 insertions(+), 23 deletions(-)
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -349,44 +349,37 @@ more:
dout("striped_read %llu~%llu (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 %llu\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;
}
Patches currently in stable-queue which might be from [email protected] are
queue-3.10/ceph-add-check-returned-value-on-func-ceph_calc_ceph_pg.patch
queue-3.10/ceph-free-mdsc-if-alloc-mdsc-mdsmap-failed.patch
queue-3.10/ceph-fix-bugs-about-handling-short-read-for-sync-read-mode.patch
queue-3.10/ceph-allow-sync_read-write-return-partial-successed-size-of-read-write.patch
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