nilfs2: get rid of private page allocator
Previously, nilfs was cloning pages for mmapped region to freeze their
data and ensure consistency of checksum during writeback cycles. A
private page allocator was used for this page cloning. But, we no
longer need to do that since clear_page_dirty_for_io function sets up
pte so that vm_ops->page_mkwrite function is called right before the
mmapped pages are modified and nilfs_page_mkwrite function can safely
wait for the pages to be written back to disk.
So, this stops making a copy of mmapped pages during writeback, and
eliminates the private page allocation and deallocation functions from
nilfs.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c
index 5deeadd..abbfab9 100644
--- a/fs/nilfs2/segment.c
+++ b/fs/nilfs2/segment.c
@@ -1556,83 +1556,24 @@
return 0;
}
-static int
-nilfs_copy_replace_page_buffers(struct page *page, struct list_head *out)
-{
- struct page *clone_page;
- struct buffer_head *bh, *head, *bh2;
- void *kaddr;
-
- bh = head = page_buffers(page);
-
- clone_page = nilfs_alloc_private_page(bh->b_bdev, bh->b_size, 0);
- if (unlikely(!clone_page))
- return -ENOMEM;
-
- bh2 = page_buffers(clone_page);
- kaddr = kmap_atomic(page, KM_USER0);
- do {
- if (list_empty(&bh->b_assoc_buffers))
- continue;
- get_bh(bh2);
- page_cache_get(clone_page); /* for each bh */
- memcpy(bh2->b_data, kaddr + bh_offset(bh), bh2->b_size);
- bh2->b_blocknr = bh->b_blocknr;
- list_replace(&bh->b_assoc_buffers, &bh2->b_assoc_buffers);
- list_add_tail(&bh->b_assoc_buffers, out);
- } while (bh = bh->b_this_page, bh2 = bh2->b_this_page, bh != head);
- kunmap_atomic(kaddr, KM_USER0);
-
- if (!TestSetPageWriteback(clone_page))
- account_page_writeback(clone_page);
- unlock_page(clone_page);
-
- return 0;
-}
-
-static int nilfs_test_page_to_be_frozen(struct page *page)
-{
- struct address_space *mapping = page->mapping;
-
- if (!mapping || !mapping->host || S_ISDIR(mapping->host->i_mode))
- return 0;
-
- if (page_mapped(page)) {
- ClearPageChecked(page);
- return 1;
- }
- return PageChecked(page);
-}
-
-static int nilfs_begin_page_io(struct page *page, struct list_head *out)
+static void nilfs_begin_page_io(struct page *page)
{
if (!page || PageWriteback(page))
/* For split b-tree node pages, this function may be called
twice. We ignore the 2nd or later calls by this check. */
- return 0;
+ return;
lock_page(page);
clear_page_dirty_for_io(page);
set_page_writeback(page);
unlock_page(page);
-
- if (nilfs_test_page_to_be_frozen(page)) {
- int err = nilfs_copy_replace_page_buffers(page, out);
- if (unlikely(err))
- return err;
- }
- return 0;
}
-static int nilfs_segctor_prepare_write(struct nilfs_sc_info *sci,
- struct page **failed_page)
+static void nilfs_segctor_prepare_write(struct nilfs_sc_info *sci)
{
struct nilfs_segment_buffer *segbuf;
struct page *bd_page = NULL, *fs_page = NULL;
- struct list_head *list = &sci->sc_copied_buffers;
- int err;
- *failed_page = NULL;
list_for_each_entry(segbuf, &sci->sc_segbufs, sb_list) {
struct buffer_head *bh;
@@ -1662,11 +1603,7 @@
break;
}
if (bh->b_page != fs_page) {
- err = nilfs_begin_page_io(fs_page, list);
- if (unlikely(err)) {
- *failed_page = fs_page;
- goto out;
- }
+ nilfs_begin_page_io(fs_page);
fs_page = bh->b_page;
}
}
@@ -1677,11 +1614,7 @@
set_page_writeback(bd_page);
unlock_page(bd_page);
}
- err = nilfs_begin_page_io(fs_page, list);
- if (unlikely(err))
- *failed_page = fs_page;
- out:
- return err;
+ nilfs_begin_page_io(fs_page);
}
static int nilfs_segctor_write(struct nilfs_sc_info *sci,
@@ -1694,24 +1627,6 @@
return ret;
}
-static void __nilfs_end_page_io(struct page *page, int err)
-{
- if (!err) {
- if (!nilfs_page_buffers_clean(page))
- __set_page_dirty_nobuffers(page);
- ClearPageError(page);
- } else {
- __set_page_dirty_nobuffers(page);
- SetPageError(page);
- }
-
- if (buffer_nilfs_allocated(page_buffers(page))) {
- if (TestClearPageWriteback(page))
- dec_zone_page_state(page, NR_WRITEBACK);
- } else
- end_page_writeback(page);
-}
-
static void nilfs_end_page_io(struct page *page, int err)
{
if (!page)
@@ -1738,40 +1653,19 @@
return;
}
- __nilfs_end_page_io(page, err);
-}
-
-static void nilfs_clear_copied_buffers(struct list_head *list, int err)
-{
- struct buffer_head *bh, *head;
- struct page *page;
-
- while (!list_empty(list)) {
- bh = list_entry(list->next, struct buffer_head,
- b_assoc_buffers);
- page = bh->b_page;
- page_cache_get(page);
- head = bh = page_buffers(page);
- do {
- if (!list_empty(&bh->b_assoc_buffers)) {
- list_del_init(&bh->b_assoc_buffers);
- if (!err) {
- set_buffer_uptodate(bh);
- clear_buffer_dirty(bh);
- clear_buffer_delay(bh);
- clear_buffer_nilfs_volatile(bh);
- }
- brelse(bh); /* for b_assoc_buffers */
- }
- } while ((bh = bh->b_this_page) != head);
-
- __nilfs_end_page_io(page, err);
- page_cache_release(page);
+ if (!err) {
+ if (!nilfs_page_buffers_clean(page))
+ __set_page_dirty_nobuffers(page);
+ ClearPageError(page);
+ } else {
+ __set_page_dirty_nobuffers(page);
+ SetPageError(page);
}
+
+ end_page_writeback(page);
}
-static void nilfs_abort_logs(struct list_head *logs, struct page *failed_page,
- int err)
+static void nilfs_abort_logs(struct list_head *logs, int err)
{
struct nilfs_segment_buffer *segbuf;
struct page *bd_page = NULL, *fs_page = NULL;
@@ -1801,8 +1695,6 @@
}
if (bh->b_page != fs_page) {
nilfs_end_page_io(fs_page, err);
- if (fs_page && fs_page == failed_page)
- return;
fs_page = bh->b_page;
}
}
@@ -1821,12 +1713,11 @@
list_splice_tail_init(&sci->sc_write_logs, &logs);
ret = nilfs_wait_on_logs(&logs);
- nilfs_abort_logs(&logs, NULL, ret ? : err);
+ nilfs_abort_logs(&logs, ret ? : err);
list_splice_tail_init(&sci->sc_segbufs, &logs);
nilfs_cancel_segusage(&logs, nilfs->ns_sufile);
nilfs_free_incomplete_logs(&logs, nilfs);
- nilfs_clear_copied_buffers(&sci->sc_copied_buffers, err);
if (sci->sc_stage.flags & NILFS_CF_SUFREED) {
ret = nilfs_sufile_cancel_freev(nilfs->ns_sufile,
@@ -1920,8 +1811,6 @@
nilfs_end_page_io(fs_page, 0);
- nilfs_clear_copied_buffers(&sci->sc_copied_buffers, 0);
-
nilfs_drop_collected_inodes(&sci->sc_dirty_files);
if (nilfs_doing_gc())
@@ -2024,7 +1913,6 @@
static int nilfs_segctor_do_construct(struct nilfs_sc_info *sci, int mode)
{
struct the_nilfs *nilfs = sci->sc_super->s_fs_info;
- struct page *failed_page;
int err;
sci->sc_stage.scnt = NILFS_ST_INIT;
@@ -2079,11 +1967,7 @@
nilfs_segctor_update_segusage(sci, nilfs->ns_sufile);
/* Write partial segments */
- err = nilfs_segctor_prepare_write(sci, &failed_page);
- if (err) {
- nilfs_abort_logs(&sci->sc_segbufs, failed_page, err);
- goto failed_to_write;
- }
+ nilfs_segctor_prepare_write(sci);
nilfs_add_checksums_on_logs(&sci->sc_segbufs,
nilfs->ns_crc_seed);
@@ -2685,7 +2569,6 @@
INIT_LIST_HEAD(&sci->sc_segbufs);
INIT_LIST_HEAD(&sci->sc_write_logs);
INIT_LIST_HEAD(&sci->sc_gc_inodes);
- INIT_LIST_HEAD(&sci->sc_copied_buffers);
init_timer(&sci->sc_timer);
sci->sc_interval = HZ * NILFS_SC_DEFAULT_TIMEOUT;
@@ -2739,8 +2622,6 @@
if (flag || !nilfs_segctor_confirm(sci))
nilfs_segctor_write_out(sci);
- WARN_ON(!list_empty(&sci->sc_copied_buffers));
-
if (!list_empty(&sci->sc_dirty_files)) {
nilfs_warning(sci->sc_super, __func__,
"dirty file(s) after the final construction\n");