ext4: make ext_debug() implementation to use pr_debug()

ext_debug() msgs could be helpful, provided those could be enabled
without recompiling kernel and also if we could selectively enable
only required prints for case by case debugging.

So make ext_debug() implementation use pr_debug().
Also change ext_debug() to be defined with CONFIG_EXT4_DEBUG.
So EXT_DEBUG macro now mostly remain for below 3 functions.
ext4_ext_show_path/leaf/move() (whose print msgs use ext_debug()
which again could be dynamically enabled using pr_debug())

This also changes the ext_debug() to take inode as a parameter
to add inode no. in all of it's msgs.
Prints additional info like process name / pid, superblock id etc.
This also removes any explicit function names passed in ext_debug().
Since ext_debug() on it's own prints file, func and line no.
Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
Link: https://lore.kernel.org/r/d31dc189b0aeda9384fe7665e36da7cd8c61571f.1589086800.git.riteshh@linux.ibm.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/Kconfig

@@ -99,7 +99,7 @@ config EXT4_DEBUG
 	  Enables run-time debugging support for the ext4 filesystem.
 
 	  If you select Y here, then you will be able to turn on debugging
-	  using dynamic debug control for mb_debug() msgs.
+	  using dynamic debug control for mb_debug() / ext_debug() msgs.
 
 config EXT4_KUNIT_TESTS
 	tristate "KUnit tests for ext4"

fs/ext4/ext4.h

@@ -80,14 +80,22 @@
 #define ext4_debug(fmt, ...)	no_printk(fmt, ##__VA_ARGS__)
 #endif
 
+ /*
+  * Turn on EXT_DEBUG to enable ext4_ext_show_path/leaf/move in extents.c
+  */
+#define EXT_DEBUG__
+
 /*
- * Turn on EXT_DEBUG to get lots of info about extents operations.
+ * Dynamic printk for controlled extents debugging.
  */
-#define EXT_DEBUG__
-#ifdef EXT_DEBUG
-#define ext_debug(fmt, ...)	printk(fmt, ##__VA_ARGS__)
+#ifdef CONFIG_EXT4_DEBUG
+#define ext_debug(ino, fmt, ...)					\
+	pr_debug("[%s/%d] EXT4-fs (%s): ino %lu: (%s, %d): %s:" fmt,	\
+		 current->comm, task_pid_nr(current),			\
+		 ino->i_sb->s_id, ino->i_ino, __FILE__, __LINE__,	\
+		 __func__, ##__VA_ARGS__)
 #else
-#define ext_debug(fmt, ...)	no_printk(fmt, ##__VA_ARGS__)
+#define ext_debug(ino, fmt, ...)	no_printk(fmt, ##__VA_ARGS__)
 #endif
 
 /* data type for block offset of block group */

fs/ext4/inode.c

@@ -501,9 +501,8 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode,
 #endif
 
 	map->m_flags = 0;
-	ext_debug("ext4_map_blocks(): inode %lu, flag %d, max_blocks %u,"
-		  "logical block %lu\n", inode->i_ino, flags, map->m_len,
-		  (unsigned long) map->m_lblk);
+	ext_debug(inode, "flag 0x%x, max_blocks %u, logical block %lu\n",
+		  flags, map->m_len, (unsigned long) map->m_lblk);
 
 	/*
 	 * ext4_map_blocks returns an int, and m_len is an unsigned int
@@ -734,8 +733,7 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode,
 	}
 
 	if (retval < 0)
-		ext_debug("failed for inode %lu with err %d\n",
-			  inode->i_ino, retval);
+		ext_debug(inode, "failed with err %d\n", retval);
 	return retval;
 }
 
@@ -1691,8 +1689,7 @@ static int ext4_da_map_blocks(struct inode *inode, sector_t iblock,
 		invalid_block = ~0;
 
 	map->m_flags = 0;
-	ext_debug("ext4_da_map_blocks(): inode %lu, max_blocks %u,"
-		  "logical block %lu\n", inode->i_ino, map->m_len,
+	ext_debug(inode, "max_blocks %u, logical block %lu\n", map->m_len,
 		  (unsigned long) map->m_lblk);
 
 	/* Lookup extent status tree firstly */