ext4: Add new tracepoint: trace_ext4_da_write_pages()

Add a new tracepoint which shows the pages that will be written using
write_cache_pages() by ext4_da_writepages().

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

3 files changed, 50 insertions, 12 deletions

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 41a76e163b99..81014f4ed22d 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -114,6 +114,21 @@ struct ext4_allocation_request {
 };
 
 /*
+ * For delayed allocation tracking
+ */
+struct mpage_da_data {
+        struct inode *inode;
+        sector_t b_blocknr;             /* start block number of extent */
+        size_t b_size;                  /* size of extent */
+        unsigned long b_state;          /* state of the extent */
+        unsigned long first_page, next_page;    /* extent of pages */
+        struct writeback_control *wbc;
+        int io_done;
+        int pages_written;
+        int retval;
+};
+
+/*
  * Special inodes numbers
  */
 #define EXT4_BAD_INO             1      /* Bad blocks inode */
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index ff659e757578..17802a96af9f 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1875,18 +1875,6 @@ static void ext4_da_page_release_reservation(struct page *page,
  * Delayed allocation stuff
  */
 
-struct mpage_da_data {
-        struct inode *inode;
-        sector_t b_blocknr;             /* start block number of extent */
-        size_t b_size;                  /* size of extent */
-        unsigned long b_state;          /* state of the extent */
-        unsigned long first_page, next_page;    /* extent of pages */
-        struct writeback_control *wbc;
-        int io_done;
-        int pages_written;
-        int retval;
-};
-
 /*
  * mpage_da_submit_io - walks through extent of pages and try to write
  * them with writepage() call back
@@ -2863,6 +2851,7 @@ retry:
                         mpd.io_done = 1;
                         ret = MPAGE_DA_EXTENT_TAIL;
                 }
+                trace_ext4_da_write_pages(inode, &mpd);
                 wbc->nr_to_write -= mpd.pages_written;
 
                 ext4_journal_stop(handle);
diff --git a/include/trace/events/ext4.h b/include/trace/events/ext4.h
index 15051d2d1219..dd43399288ea 100644
--- a/include/trace/events/ext4.h
+++ b/include/trace/events/ext4.h
@@ -251,6 +251,40 @@ TRACE_EVENT(ext4_da_writepages,
                   __entry->range_cyclic)
 );
 
+TRACE_EVENT(ext4_da_write_pages,
+        TP_PROTO(struct inode *inode, struct mpage_da_data *mpd),
+
+        TP_ARGS(inode, mpd),
+
+        TP_STRUCT__entry(
+                __field(        dev_t,  dev                     )
+                __field(        ino_t,  ino                     )
+                __field(        __u64,  b_blocknr               )
+                __field(        __u32,  b_size                  )
+                __field(        __u32,  b_state                 )
+                __field(        unsigned long,  first_page      )
+                __field(        int,    io_done                 )
+                __field(        int,    pages_written           )
+        ),
+
+        TP_fast_assign(
+                __entry->dev            = inode->i_sb->s_dev;
+                __entry->ino            = inode->i_ino;
+                __entry->b_blocknr      = mpd->b_blocknr;
+                __entry->b_size         = mpd->b_size;
+                __entry->b_state        = mpd->b_state;
+                __entry->first_page     = mpd->first_page;
+                __entry->io_done        = mpd->io_done;
+                __entry->pages_written  = mpd->pages_written;
+        ),
+
+        TP_printk("dev %s ino %lu b_blocknr %llu b_size %u b_state 0x%04x first_page %lu io_done %d pages_written %d",
+                  jbd2_dev_to_name(__entry->dev), __entry->ino,
+                  __entry->b_blocknr, __entry->b_size,
+                  __entry->b_state, __entry->first_page,
+                  __entry->io_done, __entry->pages_written)
+);
+
 TRACE_EVENT(ext4_da_writepages_result,
         TP_PROTO(struct inode *inode, struct writeback_control *wbc,
                         int ret, int pages_written),