[PATCH mmotm] nilfs2: fix miss-sync issue for do_sync_mapping_range

From: Ryusuke Konishi
Date: Tue Jan 13 2009 - 23:31:37 EST

Chris Mason pointed out that there is a miss sync issue in
nilfs_writepages():

On Wed, 17 Dec 2008 21:52:55 -0500, Chris Mason wrote:
> It looks like nilfs_writepage ignores WB_SYNC_NONE, which is used by
> do_sync_mapping_range().

where WB_SYNC_NONE in do_sync_mapping_range() was replaced with
WB_SYNC_ALL by a Nick's patch
(commit: ee53a891f47444c53318b98dac947ede963db400).

This fixes the problem by letting nilfs_writepages() write out the log
of file data within the range if sync_mode is WB_SYNC_ALL.

This involves removal of nilfs_file_aio_write() which was previously
needed to ensure O_SYNC sync writes.

Cc: Chris Mason <chris.mason@xxxxxxxxxx>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxxxxxx>
---
fs/nilfs2/file.c | 27 ++-----------------
fs/nilfs2/inode.c | 16 ++++++-----
fs/nilfs2/segment.c | 69 ++++++++++++++++++++++++++++++++++----------------
fs/nilfs2/segment.h | 11 ++++++-
4 files changed, 68 insertions(+), 55 deletions(-)

diff --git a/fs/nilfs2/file.c b/fs/nilfs2/file.c
index c22f97c..34c751b 100644
--- a/fs/nilfs2/file.c
+++ b/fs/nilfs2/file.c
@@ -44,35 +44,14 @@ int nilfs_sync_file(struct file *file, struct dentry *dentry, int datasync)
return 0;

if (datasync)
- err = nilfs_construct_dsync_segment(inode->i_sb, inode);
+ err = nilfs_construct_dsync_segment(inode->i_sb, inode, 0,
+ LLONG_MAX);
else
err = nilfs_construct_segment(inode->i_sb);

return err;
}

-static ssize_t
-nilfs_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
- unsigned long nr_segs, loff_t pos)
-{
- struct file *file = iocb->ki_filp;
- struct inode *inode = file->f_dentry->d_inode;
- ssize_t ret;
-
- ret = generic_file_aio_write(iocb, iov, nr_segs, pos);
- if (ret <= 0)
- return ret;
-
- if ((file->f_flags & O_SYNC) || IS_SYNC(inode)) {
- int err;
-
- err = nilfs_construct_dsync_segment(inode->i_sb, inode);
- if (unlikely(err))
- return err;
- }
- return ret;
-}
-
static int nilfs_page_mkwrite(struct vm_area_struct *vma, struct page *page)
{
struct inode *inode = vma->vm_file->f_dentry->d_inode;
@@ -158,7 +137,7 @@ struct file_operations nilfs_file_operations = {
.read = do_sync_read,
.write = do_sync_write,
.aio_read = generic_file_aio_read,
- .aio_write = nilfs_file_aio_write,
+ .aio_write = generic_file_aio_write,
.ioctl = nilfs_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = nilfs_compat_ioctl,
diff --git a/fs/nilfs2/inode.c b/fs/nilfs2/inode.c
index e29e329..4bf1e2c 100644
--- a/fs/nilfs2/inode.c
+++ b/fs/nilfs2/inode.c
@@ -24,6 +24,7 @@
#include <linux/buffer_head.h>
#include <linux/mpage.h>
#include <linux/writeback.h>
+#include <linux/uio.h>
#include "nilfs.h"
#include "segment.h"
#include "page.h"
@@ -146,8 +147,14 @@ static int nilfs_readpages(struct file *file, struct address_space *mapping,
static int nilfs_writepages(struct address_space *mapping,
struct writeback_control *wbc)
{
- /* This empty method is required not to call generic_writepages() */
- return 0;
+ struct inode *inode = mapping->host;
+ int err = 0;
+
+ if (wbc->sync_mode == WB_SYNC_ALL)
+ err = nilfs_construct_dsync_segment(inode->i_sb, inode,
+ wbc->range_start,
+ wbc->range_end);
+ return err;
}

static int nilfs_writepage(struct page *page, struct writeback_control *wbc)
@@ -226,11 +233,6 @@ nilfs_direct_IO(int rw, struct kiocb *iocb, const struct iovec *iov,
struct file *file = iocb->ki_filp;
struct inode *inode = file->f_mapping->host;
ssize_t size;
- int err;
-
- err = nilfs_construct_dsync_segment(inode->i_sb, inode);
- if (unlikely(err))
- return err;

if (rw == WRITE)
return 0;
diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c
index b4b96ac..90de8bb 100644
--- a/fs/nilfs2/segment.c
+++ b/fs/nilfs2/segment.c
@@ -669,27 +669,43 @@ struct nilfs_sc_operations nilfs_sc_dsync_ops = {

static int nilfs_lookup_dirty_data_buffers(struct inode *inode,
struct list_head *listp,
- struct nilfs_sc_info *sci)
+ struct nilfs_sc_info *sci,
+ loff_t start, loff_t end)
{
struct nilfs_segment_buffer *segbuf = sci->sc_curseg;
struct address_space *mapping = inode->i_mapping;
struct pagevec pvec;
unsigned i, ndirties = 0, nlimit;
- pgoff_t index = 0;
+ pgoff_t index = 0, last = ULONG_MAX;
int err = 0;

+ if (unlikely(start != 0 || end != LLONG_MAX)) {
+ /*
+ * A valid range is given for sync-ing data pages. The
+ * range is rounded to per-page; extra dirty buffers
+ * may be included if blocksize < pagesize.
+ */
+ index = start >> PAGE_SHIFT;
+ last = end >> PAGE_SHIFT;
+ }
nlimit = sci->sc_segbuf_nblocks -
(sci->sc_nblk_this_inc + segbuf->sb_sum.nblocks);
+ /* Remaining number of blocks within the segment */
pagevec_init(&pvec, 0);
repeat:
- if (!pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
- PAGEVEC_SIZE))
+ if (unlikely(index > last) ||
+ !pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
+ min_t(pgoff_t, last - index,
+ PAGEVEC_SIZE - 1) + 1))
return 0;

for (i = 0; i < pagevec_count(&pvec); i++) {
struct buffer_head *bh, *head;
struct page *page = pvec.pages[i];

+ if (unlikely(page->index > last))
+ break;
+
if (mapping->host) {
lock_page(page);
if (!page_has_buffers(page))
@@ -700,18 +716,21 @@ static int nilfs_lookup_dirty_data_buffers(struct inode *inode,

bh = head = page_buffers(page);
do {
- if (buffer_dirty(bh)) {
- if (ndirties > nlimit) {
- err = -E2BIG;
- break;
- }
- get_bh(bh);
- list_add_tail(&bh->b_assoc_buffers, listp);
- ndirties++;
+ if (!buffer_dirty(bh))
+ continue;
+ if (unlikely(ndirties >= nlimit)) {
+ err = -E2BIG; /*
+ * Internal code to indicate the
+ * inode has more dirty buffers.
+ */
+ goto bounded;
}
- bh = bh->b_this_page;
- } while (bh != head);
+ get_bh(bh);
+ list_add_tail(&bh->b_assoc_buffers, listp);
+ ndirties++;
+ } while (bh = bh->b_this_page, bh != head);
}
+ bounded:
pagevec_release(&pvec);
cond_resched();

@@ -1081,7 +1100,7 @@ static int nilfs_segctor_scan_file(struct nilfs_sc_info *sci,

if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
err = nilfs_lookup_dirty_data_buffers(inode, &data_buffers,
- sci);
+ sci, 0, LLONG_MAX);
if (err) {
err2 = nilfs_segctor_apply_buffers(
sci, inode, &data_buffers,
@@ -1129,7 +1148,10 @@ static int nilfs_segctor_scan_file_dsync(struct nilfs_sc_info *sci,
LIST_HEAD(data_buffers);
int err, err2;

- err = nilfs_lookup_dirty_data_buffers(inode, &data_buffers, sci);
+ err = nilfs_lookup_dirty_data_buffers(inode, &data_buffers, sci,
+ sci->sc_dsync_start,
+ sci->sc_dsync_end);
+
err2 = nilfs_segctor_apply_buffers(sci, inode, &data_buffers,
(!err || err == -E2BIG) ?
nilfs_collect_file_data : NULL);
@@ -1289,14 +1311,13 @@ static int nilfs_segctor_collect_blocks(struct nilfs_sc_info *sci, int mode)
case NILFS_ST_DSYNC:
dsync_mode:
sci->sc_curseg->sb_sum.flags |= NILFS_SS_SYNDT;
- ii = sci->sc_stage.dirty_file_ptr;
+ ii = sci->sc_dsync_inode;
if (!test_bit(NILFS_I_BUSY, &ii->i_state))
break;

err = nilfs_segctor_scan_file_dsync(sci, &ii->vfs_inode);
if (unlikely(err))
break;
- sci->sc_stage.dirty_file_ptr = NULL;
sci->sc_curseg->sb_sum.flags |= NILFS_SS_LOGEND;
sci->sc_stage.scnt = NILFS_ST_DONE;
return 0;
@@ -2637,7 +2658,9 @@ int nilfs_construct_segment(struct super_block *sb)
/**
* nilfs_construct_dsync_segment - construct a data-only logical segment
* @sb: super block
- * @inode: the inode whose data blocks should be written out
+ * @inode: inode whose data blocks should be written out
+ * @start: start byte offset
+ * @end: end byte offset (inclusive)
*
* Return Value: On success, 0 is retured. On errors, one of the following
* negative error code is returned.
@@ -2652,8 +2675,8 @@ int nilfs_construct_segment(struct super_block *sb)
*
* %-ENOMEM - Insufficient memory available.
*/
-int nilfs_construct_dsync_segment(struct super_block *sb,
- struct inode *inode)
+int nilfs_construct_dsync_segment(struct super_block *sb, struct inode *inode,
+ loff_t start, loff_t end)
{
struct nilfs_sb_info *sbi = NILFS_SB(sb);
struct nilfs_sc_info *sci = NILFS_SC(sbi);
@@ -2684,7 +2707,9 @@ int nilfs_construct_dsync_segment(struct super_block *sb,
return 0;
}
spin_unlock(&sbi->s_inode_lock);
- sci->sc_stage.dirty_file_ptr = ii;
+ sci->sc_dsync_inode = ii;
+ sci->sc_dsync_start = start;
+ sci->sc_dsync_end = end;

err = nilfs_segctor_do_construct(sci, SC_LSEG_DSYNC);

diff --git a/fs/nilfs2/segment.h b/fs/nilfs2/segment.h
index 615654b..2dd39da 100644
--- a/fs/nilfs2/segment.h
+++ b/fs/nilfs2/segment.h
@@ -93,6 +93,9 @@ struct nilfs_segsum_pointer {
* @sc_active_segments: List of active segments that were already written out
* @sc_cleaning_segments: List of segments to be freed through construction
* @sc_copied_buffers: List of copied buffers (buffer heads) to freeze data
+ * @sc_dsync_inode: inode whose data pages are written for a sync operation
+ * @sc_dsync_start: start byte offset of data pages
+ * @sc_dsync_end: end byte offset of data pages (inclusive)
* @sc_segbufs: List of segment buffers
* @sc_segbuf_nblocks: Number of available blocks in segment buffers.
* @sc_curseg: Current segment buffer
@@ -134,6 +137,10 @@ struct nilfs_sc_info {
struct list_head sc_cleaning_segments;
struct list_head sc_copied_buffers;

+ struct nilfs_inode_info *sc_dsync_inode;
+ loff_t sc_dsync_start;
+ loff_t sc_dsync_end;
+
/* Segment buffers */
struct list_head sc_segbufs;
unsigned long sc_segbuf_nblocks;
@@ -221,8 +228,8 @@ extern void nilfs_destroy_transaction_cache(void);
extern void nilfs_relax_pressure_in_lock(struct super_block *);

extern int nilfs_construct_segment(struct super_block *);
-extern int nilfs_construct_dsync_segment(struct super_block *,
- struct inode *);
+extern int nilfs_construct_dsync_segment(struct super_block *, struct inode *,
+ loff_t, loff_t);
extern void nilfs_flush_segment(struct super_block *, ino_t);
extern int nilfs_clean_segments(struct super_block *, void __user *);

--
1.5.6.5

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