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authorNick Piggin <npiggin@suse.de>2009-01-06 14:40:25 -0800
committerGreg Kroah-Hartman <gregkh@suse.de>2009-01-24 16:36:28 -0800
commit229dfbd9fb66befda9abbc7fd58bb0cafcd4d0d7 (patch)
tree196454bb358892dbe70ada39ef3f30a7abedf9f9
parentc672968cbc58367272e02bfef9647b3a215cc6c4 (diff)
downloadlinux-linaro-stable-229dfbd9fb66befda9abbc7fd58bb0cafcd4d0d7.tar.gz
fs: sync_sb_inodes fix
commit 38f21977663126fef53f5585e7f1653d8ebe55c4 upstream. Fix data integrity semantics required by sys_sync, by iterating over all inodes and waiting for any writeback pages after the initial writeout. Comments explain the exact problem. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--fs/fs-writeback.c60
1 files changed, 53 insertions, 7 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 997ff4c..9d2f9dc 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -440,6 +440,7 @@ void generic_sync_sb_inodes(struct super_block *sb,
struct writeback_control *wbc)
{
const unsigned long start = jiffies; /* livelock avoidance */
+ int sync = wbc->sync_mode == WB_SYNC_ALL;
spin_lock(&inode_lock);
if (!wbc->for_kupdate || list_empty(&sb->s_io))
@@ -516,7 +517,49 @@ void generic_sync_sb_inodes(struct super_block *sb,
if (!list_empty(&sb->s_more_io))
wbc->more_io = 1;
}
- spin_unlock(&inode_lock);
+
+ if (sync) {
+ struct inode *inode, *old_inode = NULL;
+
+ /*
+ * Data integrity sync. Must wait for all pages under writeback,
+ * because there may have been pages dirtied before our sync
+ * call, but which had writeout started before we write it out.
+ * In which case, the inode may not be on the dirty list, but
+ * we still have to wait for that writeout.
+ */
+ list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
+ struct address_space *mapping;
+
+ if (inode->i_state & (I_FREEING|I_WILL_FREE))
+ continue;
+ mapping = inode->i_mapping;
+ if (mapping->nrpages == 0)
+ continue;
+ __iget(inode);
+ spin_unlock(&inode_lock);
+ /*
+ * We hold a reference to 'inode' so it couldn't have
+ * been removed from s_inodes list while we dropped the
+ * inode_lock. We cannot iput the inode now as we can
+ * be holding the last reference and we cannot iput it
+ * under inode_lock. So we keep the reference and iput
+ * it later.
+ */
+ iput(old_inode);
+ old_inode = inode;
+
+ filemap_fdatawait(mapping);
+
+ cond_resched();
+
+ spin_lock(&inode_lock);
+ }
+ spin_unlock(&inode_lock);
+ iput(old_inode);
+ } else
+ spin_unlock(&inode_lock);
+
return; /* Leave any unwritten inodes on s_io */
}
EXPORT_SYMBOL_GPL(generic_sync_sb_inodes);
@@ -596,13 +639,16 @@ void sync_inodes_sb(struct super_block *sb, int wait)
.range_start = 0,
.range_end = LLONG_MAX,
};
- unsigned long nr_dirty = global_page_state(NR_FILE_DIRTY);
- unsigned long nr_unstable = global_page_state(NR_UNSTABLE_NFS);
- wbc.nr_to_write = nr_dirty + nr_unstable +
- (inodes_stat.nr_inodes - inodes_stat.nr_unused) +
- nr_dirty + nr_unstable;
- wbc.nr_to_write += wbc.nr_to_write / 2; /* Bit more for luck */
+ if (!wait) {
+ unsigned long nr_dirty = global_page_state(NR_FILE_DIRTY);
+ unsigned long nr_unstable = global_page_state(NR_UNSTABLE_NFS);
+
+ wbc.nr_to_write = nr_dirty + nr_unstable +
+ (inodes_stat.nr_inodes - inodes_stat.nr_unused);
+ } else
+ wbc.nr_to_write = LONG_MAX; /* doesn't actually matter */
+
sync_sb_inodes(sb, &wbc);
}