ceph: fix "range cyclic" mode writepages

In range cyclic mode, writepages() should first write dirty pages
in range [writeback_index, (pgoff_t)-1], then write pages in range
[0, writeback_index -1]. Besides, if writepages() encounters a page
that beyond EOF, it should restart from the beginning.

Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

1 files changed, 24 insertions, 17 deletions

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 221df531b0c3..4a54f7369f51 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -781,16 +781,15 @@ static int ceph_writepages_start(struct address_space *mapping,
         struct ceph_inode_info *ci = ceph_inode(inode);
         struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
         struct ceph_vino vino = ceph_vino(inode);
-        pgoff_t index, start, end;
-        int range_whole = 0;
-        int should_loop = 1;
+        pgoff_t index, start_index, end;
         struct ceph_snap_context *snapc = NULL, *last_snapc = NULL, *pgsnapc;
         struct pagevec pvec;
-        int done = 0;
         int rc = 0;
         unsigned int wsize = i_blocksize(inode);
         struct ceph_osd_request *req = NULL;
         struct ceph_writeback_ctl ceph_wbc;
+        bool should_loop, range_whole = false;
+        bool stop, done = false;
 
         dout("writepages_start %p (mode=%s)\n", inode,
              wbc->sync_mode == WB_SYNC_NONE ? "NONE" :
@@ -810,20 +809,22 @@ static int ceph_writepages_start(struct address_space *mapping,
 
         pagevec_init(&pvec, 0);
 
+        start_index = wbc->range_cyclic ? mapping->writeback_index : 0;
+
         /* where to start/end? */
         if (wbc->range_cyclic) {
-                start = mapping->writeback_index; /* Start from prev offset */
+                index = start_index;
                 end = -1;
-                dout(" cyclic, start at %lu\n", start);
+                should_loop = (index > 0);
+                dout(" cyclic, start at %lu\n", index);
         } else {
-                start = wbc->range_start >> PAGE_SHIFT;
+                index = wbc->range_start >> PAGE_SHIFT;
                 end = wbc->range_end >> PAGE_SHIFT;
                 if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
-                        range_whole = 1;
-                should_loop = 0;
-                dout(" not cyclic, %lu to %lu\n", start, end);
+                        range_whole = true;
+                should_loop = false;
+                dout(" not cyclic, %lu to %lu\n", index, end);
         }
-        index = start;
 
 retry:
         /* find oldest snap context with dirty data */
@@ -847,7 +848,8 @@ retry:
         }
         last_snapc = snapc;
 
-        while (!done && index <= end) {
+        stop = false;
+        while (!stop && index <= end) {
                 int num_ops = 0, op_idx;
                 unsigned i, pvec_pages, max_pages, locked_pages = 0;
                 struct page **pages = NULL, **data_pages;
@@ -885,9 +887,11 @@ get_more_pages:
                                 unlock_page(page);
                                 continue;
                         }
-                        if (!wbc->range_cyclic && page->index > end) {
+                        if (page->index > end) {
                                 dout("end of range %p\n", page);
-                                done = 1;
+                                /* can't be range_cyclic (1st pass) because
+                                 * end == -1 in that case. */
+                                stop = done = true;
                                 unlock_page(page);
                                 break;
                         }
@@ -899,7 +903,8 @@ get_more_pages:
                         if (page_offset(page) >= ceph_wbc.i_size) {
                                 dout("%p page eof %llu\n",
                                      page, ceph_wbc.i_size);
-                                done = 1;
+                                /* not done if range_cyclic */
+                                stop = true;
                                 unlock_page(page);
                                 break;
                         }
@@ -1132,7 +1137,7 @@ new_request:
                         goto new_request;
 
                 if (wbc->nr_to_write <= 0)
-                        done = 1;
+                        stop = done = true;
 
 release_pvec_pages:
                 dout("pagevec_release on %d pages (%p)\n", (int)pvec.nr,
@@ -1146,7 +1151,9 @@ release_pvec_pages:
         if (should_loop && !done) {
                 /* more to do; loop back to beginning of file */
                 dout("writepages looping back to beginning of file\n");
-                should_loop = 0;
+                should_loop = false;
+                end = start_index - 1;
+
                 index = 0;
                 goto retry;
         }