ext4: add more tracepoints and use dev_t in the trace buffer

- Add more ext4 tracepoints.
- Change ext4 tracepoints to use dev_t field with MAJOR/MINOR macros
so that we can save 4 bytes in the ring buffer on some platforms.
- Add sync_mode to ext4_da_writepages, ext4_da_write_pages, and
ext4_da_writepages_result tracepoints. Also remove for_reclaim
field from ext4_da_writepages since it is usually not very useful.

Signed-off-by: Jiaying Zhang <jiayingz@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

fs/ext4/balloc.c

@@ -21,6 +21,8 @@
 #include "ext4_jbd2.h"
 #include "mballoc.h"
 
+#include <trace/events/ext4.h>
+
 /*
  * balloc.c contains the blocks allocation and deallocation routines
  */
@@ -342,6 +344,7 @@ ext4_read_block_bitmap(struct super_block *sb, ext4_group_t block_group)
 	 * We do it here so the bitmap uptodate bit
 	 * get set with buffer lock held.
 	 */
+	trace_ext4_read_block_bitmap_load(sb, block_group);
 	set_bitmap_uptodate(bh);
 	if (bh_submit_read(bh) < 0) {
 		put_bh(bh);

fs/ext4/extents.c

@@ -44,6 +44,8 @@
 #include "ext4_jbd2.h"
 #include "ext4_extents.h"
 
+#include <trace/events/ext4.h>
+
 static int ext4_ext_truncate_extend_restart(handle_t *handle,
 					    struct inode *inode,
 					    int needed)
@@ -664,6 +666,8 @@ ext4_ext_find_extent(struct inode *inode, ext4_lblk_t block,
 		if (unlikely(!bh))
 			goto err;
 		if (!bh_uptodate_or_lock(bh)) {
+			trace_ext4_ext_load_extent(inode, block,
+						path[ppos].p_block);
 			if (bh_submit_read(bh) < 0) {
 				put_bh(bh);
 				goto err;
@@ -3297,14 +3301,15 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
 	struct ext4_ext_path *path = NULL;
 	struct ext4_extent_header *eh;
 	struct ext4_extent newex, *ex;
-	ext4_fsblk_t newblock;
+	ext4_fsblk_t newblock = 0;
 	int err = 0, depth, ret;
 	unsigned int allocated = 0;
 	struct ext4_allocation_request ar;
 	ext4_io_end_t *io = EXT4_I(inode)->cur_aio_dio;
 
 	ext_debug("blocks %u/%u requested for inode %lu\n",
 		  map->m_lblk, map->m_len, inode->i_ino);
+	trace_ext4_ext_map_blocks_enter(inode, map->m_lblk, map->m_len, flags);
 
 	/* check in cache */
 	if (ext4_ext_in_cache(inode, map->m_lblk, &newex)) {
@@ -3525,6 +3530,8 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
 		ext4_ext_drop_refs(path);
 		kfree(path);
 	}
+	trace_ext4_ext_map_blocks_exit(inode, map->m_lblk,
+		newblock, map->m_len, err ? err : allocated);
 	return err ? err : allocated;
 }
 
@@ -3658,6 +3665,7 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
 	if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
 		return -EOPNOTSUPP;
 
+	trace_ext4_fallocate_enter(inode, offset, len, mode);
 	map.m_lblk = offset >> blkbits;
 	/*
 	 * We can't just convert len to max_blocks because
@@ -3673,6 +3681,7 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
 	ret = inode_newsize_ok(inode, (len + offset));
 	if (ret) {
 		mutex_unlock(&inode->i_mutex);
+		trace_ext4_fallocate_exit(inode, offset, max_blocks, ret);
 		return ret;
 	}
 retry:
@@ -3717,6 +3726,8 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
 		goto retry;
 	}
 	mutex_unlock(&inode->i_mutex);
+	trace_ext4_fallocate_exit(inode, offset, max_blocks,
+				ret > 0 ? ret2 : ret);
 	return ret > 0 ? ret2 : ret;
 }
 

fs/ext4/fsync.c

@@ -164,20 +164,20 @@ int ext4_sync_file(struct file *file, int datasync)
 
 	J_ASSERT(ext4_journal_current_handle() == NULL);
 
-	trace_ext4_sync_file(file, datasync);
+	trace_ext4_sync_file_enter(file, datasync);
 
 	if (inode->i_sb->s_flags & MS_RDONLY)
 		return 0;
 
 	ret = ext4_flush_completed_IO(inode);
 	if (ret < 0)
-		return ret;
+		goto out;
 
 	if (!journal) {
 		ret = generic_file_fsync(file, datasync);
 		if (!ret && !list_empty(&inode->i_dentry))
 			ext4_sync_parent(inode);
-		return ret;
+		goto out;
 	}
 
 	/*
@@ -194,8 +194,10 @@ int ext4_sync_file(struct file *file, int datasync)
 	 *  (they were dirtied by commit).  But that's OK - the blocks are
 	 *  safe in-journal, which is all fsync() needs to ensure.
 	 */
-	if (ext4_should_journal_data(inode))
-		return ext4_force_commit(inode->i_sb);
+	if (ext4_should_journal_data(inode)) {
+		ret = ext4_force_commit(inode->i_sb);
+		goto out;
+	}
 
 	commit_tid = datasync ? ei->i_datasync_tid : ei->i_sync_tid;
 	if (jbd2_log_start_commit(journal, commit_tid)) {
@@ -215,5 +217,7 @@ int ext4_sync_file(struct file *file, int datasync)
 		ret = jbd2_log_wait_commit(journal, commit_tid);
 	} else if (journal->j_flags & JBD2_BARRIER)
 		blkdev_issue_flush(inode->i_sb->s_bdev, GFP_KERNEL, NULL);
+ out:
+	trace_ext4_sync_file_exit(inode, ret);
 	return ret;
 }

fs/ext4/ialloc.c

@@ -152,6 +152,7 @@ ext4_read_inode_bitmap(struct super_block *sb, ext4_group_t block_group)
 	 * We do it here so the bitmap uptodate bit
 	 * get set with buffer lock held.
 	 */
+	trace_ext4_load_inode_bitmap(sb, block_group);
 	set_bitmap_uptodate(bh);
 	if (bh_submit_read(bh) < 0) {
 		put_bh(bh);

fs/ext4/inode.c

@@ -973,6 +973,7 @@ static int ext4_ind_map_blocks(handle_t *handle, struct inode *inode,
 	int count = 0;
 	ext4_fsblk_t first_block = 0;
 
+	trace_ext4_ind_map_blocks_enter(inode, map->m_lblk, map->m_len, flags);
 	J_ASSERT(!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)));
 	J_ASSERT(handle != NULL || (flags & EXT4_GET_BLOCKS_CREATE) == 0);
 	depth = ext4_block_to_path(inode, map->m_lblk, offsets,
@@ -1058,6 +1059,8 @@ static int ext4_ind_map_blocks(handle_t *handle, struct inode *inode,
 		partial--;
 	}
 out:
+	trace_ext4_ind_map_blocks_exit(inode, map->m_lblk,
+				map->m_pblk, map->m_len, err);
 	return err;
 }
 
@@ -3379,6 +3382,7 @@ static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
 
 static int ext4_readpage(struct file *file, struct page *page)
 {
+	trace_ext4_readpage(page);
 	return mpage_readpage(page, ext4_get_block);
 }
 
@@ -3413,6 +3417,8 @@ static void ext4_invalidatepage(struct page *page, unsigned long offset)
 {
 	journal_t *journal = EXT4_JOURNAL(page->mapping->host);
 
+	trace_ext4_invalidatepage(page, offset);
+
 	/*
 	 * free any io_end structure allocated for buffers to be discarded
 	 */
@@ -3434,6 +3440,8 @@ static int ext4_releasepage(struct page *page, gfp_t wait)
 {
 	journal_t *journal = EXT4_JOURNAL(page->mapping->host);
 
+	trace_ext4_releasepage(page);
+
 	WARN_ON(PageChecked(page));
 	if (!page_has_buffers(page))
 		return 0;
@@ -3792,11 +3800,16 @@ static ssize_t ext4_direct_IO(int rw, struct kiocb *iocb,
 {
 	struct file *file = iocb->ki_filp;
 	struct inode *inode = file->f_mapping->host;
+	ssize_t ret;
 
+	trace_ext4_direct_IO_enter(inode, offset, iov_length(iov, nr_segs), rw);
 	if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))
-		return ext4_ext_direct_IO(rw, iocb, iov, offset, nr_segs);
-
-	return ext4_ind_direct_IO(rw, iocb, iov, offset, nr_segs);
+		ret = ext4_ext_direct_IO(rw, iocb, iov, offset, nr_segs);
+	else
+		ret = ext4_ind_direct_IO(rw, iocb, iov, offset, nr_segs);
+	trace_ext4_direct_IO_exit(inode, offset,
+				iov_length(iov, nr_segs), rw, ret);
+	return ret;
 }
 
 /*
@@ -4425,6 +4438,8 @@ void ext4_truncate(struct inode *inode)
 	ext4_lblk_t last_block;
 	unsigned blocksize = inode->i_sb->s_blocksize;
 
+	trace_ext4_truncate_enter(inode);
+
 	if (!ext4_can_truncate(inode))
 		return;
 
@@ -4435,6 +4450,7 @@ void ext4_truncate(struct inode *inode)
 
 	if (ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
 		ext4_ext_truncate(inode);
+		trace_ext4_truncate_exit(inode);
 		return;
 	}
 
@@ -4564,6 +4580,7 @@ void ext4_truncate(struct inode *inode)
 		ext4_orphan_del(handle, inode);
 
 	ext4_journal_stop(handle);
+	trace_ext4_truncate_exit(inode);
 }
 
 /*
@@ -4695,6 +4712,7 @@ static int __ext4_get_inode_loc(struct inode *inode,
 		 * has in-inode xattrs, or we don't have this inode in memory.
 		 * Read the block from disk.
 		 */
+		trace_ext4_load_inode(inode);
 		get_bh(bh);
 		bh->b_end_io = end_buffer_read_sync;
 		submit_bh(READ_META, bh);

fs/ext4/namei.c

@@ -40,6 +40,7 @@
 #include "xattr.h"
 #include "acl.h"
 
+#include <trace/events/ext4.h>
 /*
  * define how far ahead to read directories while searching them.
  */
@@ -2183,6 +2184,7 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry)
 	struct ext4_dir_entry_2 *de;
 	handle_t *handle;
 
+	trace_ext4_unlink_enter(dir, dentry);
 	/* Initialize quotas before so that eventual writes go
 	 * in separate transaction */
 	dquot_initialize(dir);
@@ -2228,6 +2230,7 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry)
 end_unlink:
 	ext4_journal_stop(handle);
 	brelse(bh);
+	trace_ext4_unlink_exit(dentry, retval);
 	return retval;
 }