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authorAlex Elder <elder@inktank.com>2013-03-30 15:09:59 -0500
committerSage Weil <sage@inktank.com>2013-05-01 21:17:39 -0700
commit5df521b1eecf276c4bae8ffb7945acef45530449 (patch)
treeb6a8434361e786d81b364aa202cc40628eb60b65 /net/ceph/messenger.c
parent1190bf06a6b033384a65b5acdb1193d41cd257a6 (diff)
libceph: page offset must be less than page size
Currently ceph_msg_data_pages_advance() allows the page offset value to be PAGE_SIZE, apparently assuming ceph_msg_data_pages_next() will treat it as 0. But that doesn't happen, and the result led to a helpful assertion failure. Change ceph_msg_data_pages_advance() to truncate the offset to 0 before returning if it reaches PAGE_SIZE. Make a few other minor adjustments in this area (comments and a better assertion) while modifying it. This resolves a second issue described in: http://tracker.ceph.com/issues/4598 Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Sage Weil <sage@inktank.com>
Diffstat (limited to 'net/ceph/messenger.c')
-rw-r--r--net/ceph/messenger.c14
1 files changed, 7 insertions, 7 deletions
diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index 24f3aba34800..198b9026288e 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -766,8 +766,8 @@ static struct page *ceph_msg_data_bio_next(struct ceph_msg_data *data,
*length = cursor->resid;
else
*length = (size_t) (bio_vec->bv_len - cursor->vector_offset);
- BUG_ON(*length > PAGE_SIZE);
BUG_ON(*length > cursor->resid);
+ BUG_ON(*page_offset + *length > PAGE_SIZE);
return bio_vec->bv_page;
}
@@ -876,14 +876,13 @@ static bool ceph_msg_data_pages_advance(struct ceph_msg_data *data,
/* Advance the cursor page offset */
cursor->resid -= bytes;
- cursor->page_offset += bytes;
- if (!bytes || cursor->page_offset & ~PAGE_MASK)
+ cursor->page_offset = (cursor->page_offset + bytes) & ~PAGE_MASK;
+ if (!bytes || cursor->page_offset)
return false; /* more bytes to process in the current page */
- /* Move on to the next page */
+ /* Move on to the next page; offset is already at 0 */
BUG_ON(cursor->page_index >= cursor->page_count);
- cursor->page_offset = 0;
cursor->page_index++;
cursor->last_piece = cursor->resid <= PAGE_SIZE;
@@ -934,8 +933,9 @@ static struct page *ceph_msg_data_pagelist_next(struct ceph_msg_data *data,
BUG_ON(!cursor->page);
BUG_ON(cursor->offset + cursor->resid != pagelist->length);
+ /* offset of first page in pagelist is always 0 */
*page_offset = cursor->offset & ~PAGE_MASK;
- if (cursor->last_piece) /* pagelist offset is always 0 */
+ if (cursor->last_piece)
*length = cursor->resid;
else
*length = PAGE_SIZE - *page_offset;
@@ -961,7 +961,7 @@ static bool ceph_msg_data_pagelist_advance(struct ceph_msg_data *data,
cursor->resid -= bytes;
cursor->offset += bytes;
- /* pagelist offset is always 0 */
+ /* offset of first page in pagelist is always 0 */
if (!bytes || cursor->offset & ~PAGE_MASK)
return false; /* more bytes to process in the current page */

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