ext4: pass context information to jbd2__journal_start()

So we can better understand what bits of ext4 are responsible for
long-running jbd2 handles, use jbd2__journal_start() so we can pass
context information for logging purposes.

The recommended way for finding the longer-running handles is:

   T=/sys/kernel/debug/tracing
   EVENT=$T/events/jbd2/jbd2_handle_stats
   echo "interval > 5" > $EVENT/filter
   echo 1 > $EVENT/enable

   ./run-my-fs-benchmark

   cat $T/trace > /tmp/problem-handles

This will list handles that were active for longer than 20ms.  Having
longer-running handles is bad, because a commit started at the wrong
time could stall for those 20+ milliseconds, which could delay an
fsync() or an O_SYNC operation.  Here is an example line from the
trace file describing a handle which lived on for 311 jiffies, or over
1.2 seconds:

postmark-2917  [000] ....   196.435786: jbd2_handle_stats: dev 254,32 
   tid 570 type 2 line_no 2541 interval 311 sync 0 requested_blocks 1
   dirtied_blocks 0

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 5 insertions, 5 deletions

diff --git a/fs/ext4/inline.c b/fs/ext4/inline.c
index 93a3408fc89b..bc5f871f0893 100644
--- a/fs/ext4/inline.c
+++ b/fs/ext4/inline.c
@@ -545,7 +545,7 @@ static int ext4_convert_inline_data_to_extent(struct address_space *mapping,
                 return ret;
 
 retry:
-        handle = ext4_journal_start(inode, needed_blocks);
+        handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE, needed_blocks);
         if (IS_ERR(handle)) {
                 ret = PTR_ERR(handle);
                 handle = NULL;
@@ -657,7 +657,7 @@ int ext4_try_to_write_inline_data(struct address_space *mapping,
          * The possible write could happen in the inode,
          * so try to reserve the space in inode first.
          */
-        handle = ext4_journal_start(inode, 1);
+        handle = ext4_journal_start(inode, EXT4_HT_INODE, 1);
         if (IS_ERR(handle)) {
                 ret = PTR_ERR(handle);
                 handle = NULL;
@@ -853,7 +853,7 @@ int ext4_da_write_inline_data_begin(struct address_space *mapping,
         if (ret)
                 return ret;
 
-        handle = ext4_journal_start(inode, 1);
+        handle = ext4_journal_start(inode, EXT4_HT_INODE, 1);
         if (IS_ERR(handle)) {
                 ret = PTR_ERR(handle);
                 handle = NULL;
@@ -1770,7 +1770,7 @@ void ext4_inline_data_truncate(struct inode *inode, int *has_inline)
 
 
         needed_blocks = ext4_writepage_trans_blocks(inode);
-        handle = ext4_journal_start(inode, needed_blocks);
+        handle = ext4_journal_start(inode, EXT4_HT_INODE, needed_blocks);
         if (IS_ERR(handle))
                 return;
 
@@ -1862,7 +1862,7 @@ int ext4_convert_inline_data(struct inode *inode)
         if (error)
                 return error;
 
-        handle = ext4_journal_start(inode, needed_blocks);
+        handle = ext4_journal_start(inode, EXT4_HT_WRITE_PAGE, needed_blocks);
         if (IS_ERR(handle)) {
                 error = PTR_ERR(handle);
                 goto out_free;