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authorYan, Zheng <zyan@redhat.com>2015-06-18 03:10:58 +0800
committerIlya Dryomov <idryomov@gmail.com>2015-06-25 18:30:53 +0300
commite1966b49446a43994c3f25a07d0eb4d05660b429 (patch)
tree43464087b52c41e58396f7805783bd9e627d2bfb /fs/ceph
parentd3834fefcfe5610702379d78596337875df2db5b (diff)
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ceph: fix ceph_writepages_start()
Before a page get locked, someone else can write data to the page and increase the i_size. So we should re-check the i_size after pages are locked. Signed-off-by: Yan, Zheng <zyan@redhat.com>
Diffstat (limited to 'fs/ceph')
-rw-r--r--fs/ceph/addr.c37
1 files changed, 23 insertions, 14 deletions
diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 97102038fe03..890c50971a69 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -440,7 +440,7 @@ out:
* only snap context we are allowed to write back.
*/
static struct ceph_snap_context *get_oldest_context(struct inode *inode,
- u64 *snap_size)
+ loff_t *snap_size)
{
struct ceph_inode_info *ci = ceph_inode(inode);
struct ceph_snap_context *snapc = NULL;
@@ -480,8 +480,9 @@ static int writepage_nounlock(struct page *page, struct writeback_control *wbc)
struct ceph_osd_client *osdc;
struct ceph_snap_context *snapc, *oldest;
loff_t page_off = page_offset(page);
+ loff_t snap_size = -1;
long writeback_stat;
- u64 truncate_size, snap_size = 0;
+ u64 truncate_size;
u32 truncate_seq;
int err = 0, len = PAGE_CACHE_SIZE;
@@ -516,7 +517,7 @@ static int writepage_nounlock(struct page *page, struct writeback_control *wbc)
spin_lock(&ci->i_ceph_lock);
truncate_seq = ci->i_truncate_seq;
truncate_size = ci->i_truncate_size;
- if (!snap_size)
+ if (snap_size == -1)
snap_size = i_size_read(inode);
spin_unlock(&ci->i_ceph_lock);
@@ -699,7 +700,8 @@ static int ceph_writepages_start(struct address_space *mapping,
unsigned wsize = 1 << inode->i_blkbits;
struct ceph_osd_request *req = NULL;
int do_sync = 0;
- u64 truncate_size, snap_size;
+ loff_t snap_size, i_size;
+ u64 truncate_size;
u32 truncate_seq;
/*
@@ -745,7 +747,7 @@ static int ceph_writepages_start(struct address_space *mapping,
retry:
/* find oldest snap context with dirty data */
ceph_put_snap_context(snapc);
- snap_size = 0;
+ snap_size = -1;
snapc = get_oldest_context(inode, &snap_size);
if (!snapc) {
/* hmm, why does writepages get called when there
@@ -753,16 +755,13 @@ retry:
dout(" no snap context with dirty data?\n");
goto out;
}
- if (snap_size == 0)
- snap_size = i_size_read(inode);
dout(" oldest snapc is %p seq %lld (%d snaps)\n",
snapc, snapc->seq, snapc->num_snaps);
spin_lock(&ci->i_ceph_lock);
truncate_seq = ci->i_truncate_seq;
truncate_size = ci->i_truncate_size;
- if (!snap_size)
- snap_size = i_size_read(inode);
+ i_size = i_size_read(inode);
spin_unlock(&ci->i_ceph_lock);
if (last_snapc && snapc != last_snapc) {
@@ -832,8 +831,10 @@ get_more_pages:
dout("waiting on writeback %p\n", page);
wait_on_page_writeback(page);
}
- if (page_offset(page) >= snap_size) {
- dout("%p page eof %llu\n", page, snap_size);
+ if (page_offset(page) >=
+ (snap_size == -1 ? i_size : snap_size)) {
+ dout("%p page eof %llu\n", page,
+ (snap_size == -1 ? i_size : snap_size));
done = 1;
unlock_page(page);
break;
@@ -949,10 +950,18 @@ get_more_pages:
}
/* Format the osd request message and submit the write */
-
offset = page_offset(pages[0]);
- len = min(snap_size - offset,
- (u64)locked_pages << PAGE_CACHE_SHIFT);
+ len = (u64)locked_pages << PAGE_CACHE_SHIFT;
+ if (snap_size == -1) {
+ len = min(len, (u64)i_size_read(inode) - offset);
+ /* writepages_finish() clears writeback pages
+ * according to the data length, so make sure
+ * data length covers all locked pages */
+ len = max(len, 1 +
+ ((u64)(locked_pages - 1) << PAGE_CACHE_SHIFT));
+ } else {
+ len = min(len, snap_size - offset);
+ }
dout("writepages got %d pages at %llu~%llu\n",
locked_pages, offset, len);