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Date: Sat, 7 Feb 2009 22:34:53 +0900
From: Ryusuke Konishi <konishi.ryusuke@....ntt.co.jp>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
Ryusuke Konishi <konishi.ryusuke@....ntt.co.jp>
Subject: [PATCH mmotm] nilfs2: fix segment summary corruption
With a report from David Arendt, one of the recent bug fixes
(nilfs2-fix-miss-sync-issue-for-do_sync_mapping_range.patch) turned
out to break segment summary under some conditions.
This fixes the problem and clarifies a few routines to prevent similar
regressions. Thanks to David for his ardent feedbacks.
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@....ntt.co.jp>
---
fs/nilfs2/segment.c | 81 +++++++++++++++++++++++++--------------------------
1 files changed, 40 insertions(+), 41 deletions(-)
diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c
index 90de8bb..6d66c5c 100644
--- a/fs/nilfs2/segment.c
+++ b/fs/nilfs2/segment.c
@@ -667,17 +667,16 @@ struct nilfs_sc_operations nilfs_sc_dsync_ops = {
.write_node_binfo = NULL,
};
-static int nilfs_lookup_dirty_data_buffers(struct inode *inode,
- struct list_head *listp,
- struct nilfs_sc_info *sci,
- loff_t start, loff_t end)
+static size_t nilfs_lookup_dirty_data_buffers(struct inode *inode,
+ struct list_head *listp,
+ size_t nlimit,
+ 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, last = ULONG_MAX;
- int err = 0;
+ size_t ndirties = 0;
+ int i;
if (unlikely(start != 0 || end != LLONG_MAX)) {
/*
@@ -688,16 +687,13 @@ static int nilfs_lookup_dirty_data_buffers(struct inode *inode,
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 (unlikely(index > last) ||
!pagevec_lookup_tag(&pvec, mapping, &index, PAGECACHE_TAG_DIRTY,
min_t(pgoff_t, last - index,
PAGEVEC_SIZE - 1) + 1))
- return 0;
+ return ndirties;
for (i = 0; i < pagevec_count(&pvec); i++) {
struct buffer_head *bh, *head;
@@ -718,25 +714,19 @@ static int nilfs_lookup_dirty_data_buffers(struct inode *inode,
do {
if (!buffer_dirty(bh))
continue;
- if (unlikely(ndirties >= nlimit)) {
- err = -E2BIG; /*
- * Internal code to indicate the
- * inode has more dirty buffers.
- */
- goto bounded;
- }
get_bh(bh);
list_add_tail(&bh->b_assoc_buffers, listp);
ndirties++;
+ if (unlikely(ndirties >= nlimit)) {
+ pagevec_release(&pvec);
+ cond_resched();
+ return ndirties;
+ }
} while (bh = bh->b_this_page, bh != head);
}
- bounded:
pagevec_release(&pvec);
cond_resched();
-
- if (!err)
- goto repeat;
- return err;
+ goto repeat;
}
static void nilfs_lookup_dirty_node_buffers(struct inode *inode,
@@ -1090,23 +1080,31 @@ static int nilfs_segctor_apply_buffers(struct nilfs_sc_info *sci,
return err;
}
+static size_t nilfs_segctor_buffer_rest(struct nilfs_sc_info *sci)
+{
+ /* Remaining number of blocks within segment buffer */
+ return sci->sc_segbuf_nblocks -
+ (sci->sc_nblk_this_inc + sci->sc_curseg->sb_sum.nblocks);
+}
+
static int nilfs_segctor_scan_file(struct nilfs_sc_info *sci,
struct inode *inode,
struct nilfs_sc_operations *sc_ops)
{
LIST_HEAD(data_buffers);
LIST_HEAD(node_buffers);
- int err, err2;
+ int err;
if (!(sci->sc_stage.flags & NILFS_CF_NODE)) {
- err = nilfs_lookup_dirty_data_buffers(inode, &data_buffers,
- sci, 0, LLONG_MAX);
- if (err) {
- err2 = nilfs_segctor_apply_buffers(
+ size_t n, rest = nilfs_segctor_buffer_rest(sci);
+
+ n = nilfs_lookup_dirty_data_buffers(
+ inode, &data_buffers, rest + 1, 0, LLONG_MAX);
+ if (n > rest) {
+ err = nilfs_segctor_apply_buffers(
sci, inode, &data_buffers,
- err == -E2BIG ? sc_ops->collect_data : NULL);
- if (err == -E2BIG)
- err = err2;
+ sc_ops->collect_data);
+ BUG_ON(!err); /* always receive -E2BIG or true error */
goto break_or_fail;
}
}
@@ -1146,19 +1144,20 @@ static int nilfs_segctor_scan_file_dsync(struct nilfs_sc_info *sci,
struct inode *inode)
{
LIST_HEAD(data_buffers);
- int err, err2;
+ size_t n, rest = nilfs_segctor_buffer_rest(sci);
+ int err;
- err = nilfs_lookup_dirty_data_buffers(inode, &data_buffers, sci,
- sci->sc_dsync_start,
- sci->sc_dsync_end);
+ n = nilfs_lookup_dirty_data_buffers(inode, &data_buffers, rest + 1,
+ 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);
- if (err == -E2BIG)
- err = err2;
- if (!err)
+ err = nilfs_segctor_apply_buffers(sci, inode, &data_buffers,
+ nilfs_collect_file_data);
+ if (!err) {
nilfs_segctor_end_finfo(sci, inode);
+ BUG_ON(n > rest);
+ /* always receive -E2BIG or true error if n > rest */
+ }
return err;
}
--
1.5.6.5
--
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