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>

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 221df531b0c3133ce9fb71ef8f30e644b0cf1987..4a54f7369f51a597f409dfac55fea03d681c2a25 100644 (file)
--- 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;
        }