1 files changed, 56 insertions, 36 deletions

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index d0ff0b8cf309..e5eaa62fd17f 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -421,9 +421,6 @@ __writeback_single_inode(struct inode *inode, struct writeback_control *wbc)
  * If we're a pdlfush thread, then implement pdflush collision avoidance
  * against the entire list.
  *
- * WB_SYNC_HOLD is a hack for sys_sync(): reattach the inode to sb->s_dirty so
- * that it can be located for waiting on in __writeback_single_inode().
- *
  * If `bdi' is non-zero then we're being asked to writeback a specific queue.
  * This function assumes that the blockdev superblock's inodes are backed by
  * a variety of queues, so all inodes are searched.  For other superblocks,
@@ -443,6 +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))
@@ -499,10 +497,6 @@ void generic_sync_sb_inodes(struct super_block *sb,
                 __iget(inode);
                 pages_skipped = wbc->pages_skipped;
                 __writeback_single_inode(inode, wbc);
-                if (wbc->sync_mode == WB_SYNC_HOLD) {
-                        inode->dirtied_when = jiffies;
-                        list_move(&inode->i_list, &sb->s_dirty);
-                }
                 if (current_is_pdflush())
                         writeback_release(bdi);
                 if (wbc->pages_skipped != pages_skipped) {
@@ -523,7 +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);
@@ -588,8 +624,7 @@ restart:
 
 /*
  * writeback and wait upon the filesystem's dirty inodes.  The caller will
- * do this in two passes - one to write, and one to wait.  WB_SYNC_HOLD is
- * used to park the written inodes on sb->s_dirty for the wait pass.
+ * do this in two passes - one to write, and one to wait.
  *
  * A finite limit is set on the number of pages which will be written.
  * To prevent infinite livelock of sys_sync().
@@ -600,30 +635,21 @@ restart:
 void sync_inodes_sb(struct super_block *sb, int wait)
 {
         struct writeback_control wbc = {
-                .sync_mode      = wait ? WB_SYNC_ALL : WB_SYNC_HOLD,
+                .sync_mode      = wait ? WB_SYNC_ALL : WB_SYNC_NONE,
                 .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 */
-        sync_sb_inodes(sb, &wbc);
-}
+        if (!wait) {
+                unsigned long nr_dirty = global_page_state(NR_FILE_DIRTY);
+                unsigned long nr_unstable = global_page_state(NR_UNSTABLE_NFS);
 
-/*
- * Rather lame livelock avoidance.
- */
-static void set_sb_syncing(int val)
-{
-        struct super_block *sb;
-        spin_lock(&sb_lock);
-        list_for_each_entry_reverse(sb, &super_blocks, s_list)
-                sb->s_syncing = val;
-        spin_unlock(&sb_lock);
+                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);
 }
 
 /**
@@ -652,9 +678,6 @@ static void __sync_inodes(int wait)
         spin_lock(&sb_lock);
 restart:
         list_for_each_entry(sb, &super_blocks, s_list) {
-                if (sb->s_syncing)
-                        continue;
-                sb->s_syncing = 1;
                 sb->s_count++;
                 spin_unlock(&sb_lock);
                 down_read(&sb->s_umount);
@@ -672,13 +695,10 @@ restart:
 
 void sync_inodes(int wait)
 {
-        set_sb_syncing(0);
         __sync_inodes(0);
 
-        if (wait) {
-                set_sb_syncing(0);
+        if (wait)
                 __sync_inodes(1);
-        }
 }
 
 /**