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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>
This commit is contained in:
Ryusuke Konishi 2011-04-04 12:53:28 +09:00
parent eaae0f37d8
commit 1cb2d38cb3
6 changed files with 18 additions and 207 deletions
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1
fs/nilfs2/file.c
View File

@ -111,7 +111,6 @@ static int nilfs_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
nilfs_transaction_commit(inode->i_sb);
mapped:
SetPageChecked(page);
wait_on_page_writeback(page);
return VM_FAULT_LOCKED;
}

53
fs/nilfs2/page.c
View File

@ -37,8 +37,7 @@
#define NILFS_BUFFER_INHERENT_BITS \
((1UL << BH_Uptodate) | (1UL << BH_Mapped) | (1UL << BH_NILFS_Node) | \
(1UL << BH_NILFS_Volatile) | (1UL << BH_NILFS_Allocated) | \
(1UL << BH_NILFS_Checked))
(1UL << BH_NILFS_Volatile) | (1UL << BH_NILFS_Checked))
static struct buffer_head *
__nilfs_get_page_block(struct page *page, unsigned long block, pgoff_t index,
@ -216,56 +215,6 @@ void nilfs_page_bug(struct page *page)
}
}
/**
* nilfs_alloc_private_page - allocate a private page with buffer heads
*
* Return Value: On success, a pointer to the allocated page is returned.
* On error, NULL is returned.
*/
struct page *nilfs_alloc_private_page(struct block_device *bdev, int size,
unsigned long state)
{
struct buffer_head *bh, *head, *tail;
struct page *page;
page = alloc_page(GFP_NOFS); /* page_count of the returned page is 1 */
if (unlikely(!page))
return NULL;
lock_page(page);
head = alloc_page_buffers(page, size, 0);
if (unlikely(!head)) {
unlock_page(page);
__free_page(page);
return NULL;
}
bh = head;
do {
bh->b_state = (1UL << BH_NILFS_Allocated) | state;
tail = bh;
bh->b_bdev = bdev;
bh = bh->b_this_page;
} while (bh);
tail->b_this_page = head;
attach_page_buffers(page, head);
return page;
}
void nilfs_free_private_page(struct page *page)
{
BUG_ON(!PageLocked(page));
BUG_ON(page->mapping);
if (page_has_buffers(page) && !try_to_free_buffers(page))
NILFS_PAGE_BUG(page, "failed to free page");
unlock_page(page);
__free_page(page);
}
/**
* nilfs_copy_page -- copy the page with buffers
* @dst: destination page

4
fs/nilfs2/page.h
View File

@ -38,7 +38,6 @@ enum {
BH_NILFS_Redirected,
};
BUFFER_FNS(NILFS_Allocated, nilfs_allocated) /* nilfs private buffers */
BUFFER_FNS(NILFS_Node, nilfs_node) /* nilfs node buffers */
BUFFER_FNS(NILFS_Volatile, nilfs_volatile)
BUFFER_FNS(NILFS_Checked, nilfs_checked) /* buffer is verified */
@ -54,9 +53,6 @@ void nilfs_forget_buffer(struct buffer_head *);
void nilfs_copy_buffer(struct buffer_head *, struct buffer_head *);
int nilfs_page_buffers_clean(struct page *);
void nilfs_page_bug(struct page *);
struct page *nilfs_alloc_private_page(struct block_device *, int,
unsigned long);
void nilfs_free_private_page(struct page *);
int nilfs_copy_dirty_pages(struct address_space *, struct address_space *);
void nilfs_copy_back_pages(struct address_space *, struct address_space *);

12
fs/nilfs2/segbuf.c
View File

@ -254,18 +254,6 @@ static void nilfs_release_buffers(struct list_head *list)
list_for_each_entry_safe(bh, n, list, b_assoc_buffers) {
list_del_init(&bh->b_assoc_buffers);
if (buffer_nilfs_allocated(bh)) {
struct page *clone_page = bh->b_page;
/* remove clone page */
brelse(bh);
page_cache_release(clone_page); /* for each bh */
if (page_count(clone_page) <= 2) {
lock_page(clone_page);
nilfs_free_private_page(clone_page);
}
continue;
}
brelse(bh);
}
}

153
fs/nilfs2/segment.c
View File

@ -1556,83 +1556,24 @@ static int nilfs_segctor_assign(struct nilfs_sc_info *sci, int mode)
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 @@ static int nilfs_segctor_prepare_write(struct nilfs_sc_info *sci,
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 @@ static int nilfs_segctor_prepare_write(struct nilfs_sc_info *sci,
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 @@ static int nilfs_segctor_write(struct nilfs_sc_info *sci,
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 @@ static void nilfs_end_page_io(struct page *page, int err)
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 @@ static void nilfs_abort_logs(struct list_head *logs, struct page *failed_page,
}
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 @@ static void nilfs_segctor_abort_construction(struct nilfs_sc_info *sci,
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 @@ static void nilfs_segctor_complete_write(struct nilfs_sc_info *sci)
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 void nilfs_segctor_drop_written_files(struct nilfs_sc_info *sci,
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 @@ static int nilfs_segctor_do_construct(struct nilfs_sc_info *sci, int mode)
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 @@ static struct nilfs_sc_info *nilfs_segctor_new(struct super_block *sb,
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 @@ static void nilfs_segctor_destroy(struct nilfs_sc_info *sci)
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");

2
fs/nilfs2/segment.h
View File

@ -92,7 +92,6 @@ struct nilfs_segsum_pointer {
* @sc_nblk_inc: Block count of current generation
* @sc_dirty_files: List of files to be written
* @sc_gc_inodes: List of GC inodes having blocks to be written
* @sc_copied_buffers: List of copied buffers (buffer heads) to freeze data
* @sc_freesegs: array of segment numbers to be freed
* @sc_nfreesegs: number of segments on @sc_freesegs
* @sc_dsync_inode: inode whose data pages are written for a sync operation
@ -136,7 +135,6 @@ struct nilfs_sc_info {
struct list_head sc_dirty_files;
struct list_head sc_gc_inodes;
struct list_head sc_copied_buffers;
__u64 *sc_freesegs;
size_t sc_nfreesegs;