ext4: Remove "extents" mount option

This mount option is largely superfluous, and in fact the way it was
implemented was buggy; if a filesystem which did not have the extents
feature flag was mounted -o extents, the filesystem would attempt to
create and use extents-based file even though the extents feature flag
was not eabled.  The simplest thing to do is to nuke the mount option
entirely.  It's not all that useful to force the non-creation of new
extent-based files if the filesystem can support it.

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

Documentation/filesystems/ext4.txt

@@ -131,11 +131,6 @@ ro                   	Mount filesystem read only. Note that ext4 will
                      	mount options "ro,noload" can be used to prevent
 		     	writes to the filesystem.
 
-extents		(*)	ext4 will use extents to address file data.  The
-			file system will no longer be mountable by ext3.
-
-noextents		ext4 will not use extents for newly created files
-
 journal_checksum	Enable checksumming of the journal transactions.
 			This will allow the recovery code in e2fsck and the
 			kernel to detect corruption in the kernel.  It is a

fs/ext4/ext4.h

@@ -536,7 +536,6 @@ do {									       \
 #define EXT4_MOUNT_QUOTA		0x80000 /* Some quota option set */
 #define EXT4_MOUNT_USRQUOTA		0x100000 /* "old" user quota */
 #define EXT4_MOUNT_GRPQUOTA		0x200000 /* "old" group quota */
-#define EXT4_MOUNT_EXTENTS		0x400000 /* Extents support */
 #define EXT4_MOUNT_JOURNAL_CHECKSUM	0x800000 /* Journal checksums */
 #define EXT4_MOUNT_JOURNAL_ASYNC_COMMIT	0x1000000 /* Journal Async Commit */
 #define EXT4_MOUNT_I_VERSION            0x2000000 /* i_version support */

fs/ext4/ext4_jbd2.h

@@ -32,8 +32,8 @@
  * 5 levels of tree + root which are stored in the inode. */
 
 #define EXT4_SINGLEDATA_TRANS_BLOCKS(sb)				\
-	(EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_EXTENTS)	\
-		|| test_opt(sb, EXTENTS) ? 27U : 8U)
+	(EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_EXTENTS)   \
+	 ? 27U : 8U)
 
 /* Extended attribute operations touch at most two data buffers,
  * two bitmap buffers, and two group summaries, in addition to the inode

fs/ext4/extents.c

@@ -2247,7 +2247,7 @@ void ext4_ext_init(struct super_block *sb)
 	 * possible initialization would be here
 	 */
 
-	if (test_opt(sb, EXTENTS)) {
+	if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_EXTENTS)) {
 		printk(KERN_INFO "EXT4-fs: file extents enabled");
 #ifdef AGGRESSIVE_TEST
 		printk(", aggressive tests");
@@ -2272,7 +2272,7 @@ void ext4_ext_init(struct super_block *sb)
  */
 void ext4_ext_release(struct super_block *sb)
 {
-	if (!test_opt(sb, EXTENTS))
+	if (!EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_EXTENTS))
 		return;
 
 #ifdef EXTENTS_STATS

fs/ext4/ialloc.c

@@ -917,7 +917,7 @@ got:
 	if (err)
 		goto fail_free_drop;
 
-	if (test_opt(sb, EXTENTS)) {
+	if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_EXTENTS)) {
 		/* set extent flag only for directory, file and normal symlink*/
 		if (S_ISDIR(mode) || S_ISREG(mode) || S_ISLNK(mode)) {
 			EXT4_I(inode)->i_flags |= EXT4_EXTENTS_FL;

fs/ext4/migrate.c

@@ -459,13 +459,13 @@ int ext4_ext_migrate(struct inode *inode)
 	struct list_blocks_struct lb;
 	unsigned long max_entries;
 
-	if (!test_opt(inode->i_sb, EXTENTS))
-		/*
-		 * if mounted with noextents we don't allow the migrate
-		 */
-		return -EINVAL;
-
-	if ((EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL))
+	/*
+	 * If the filesystem does not support extents, or the inode
+	 * already is extent-based, error out.
+	 */
+	if (!EXT4_HAS_INCOMPAT_FEATURE(inode->i_sb,
+				       EXT4_FEATURE_INCOMPAT_EXTENTS) ||
+	    (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL))
 		return -EINVAL;
 
 	if (S_ISLNK(inode->i_mode) && inode->i_blocks == 0)

fs/ext4/super.c

@@ -829,8 +829,6 @@ static int ext4_show_options(struct seq_file *seq, struct vfsmount *vfs)
 		seq_puts(seq, ",journal_async_commit");
 	if (test_opt(sb, NOBH))
 		seq_puts(seq, ",nobh");
-	if (!test_opt(sb, EXTENTS))
-		seq_puts(seq, ",noextents");
 	if (test_opt(sb, I_VERSION))
 		seq_puts(seq, ",i_version");
 	if (!test_opt(sb, DELALLOC))
@@ -1011,7 +1009,7 @@ enum {
 	Opt_usrjquota, Opt_grpjquota, Opt_offusrjquota, Opt_offgrpjquota,
 	Opt_jqfmt_vfsold, Opt_jqfmt_vfsv0, Opt_quota, Opt_noquota,
 	Opt_ignore, Opt_barrier, Opt_err, Opt_resize, Opt_usrquota,
-	Opt_grpquota, Opt_extents, Opt_noextents, Opt_i_version,
+	Opt_grpquota, Opt_i_version,
 	Opt_stripe, Opt_delalloc, Opt_nodelalloc,
 	Opt_inode_readahead_blks, Opt_journal_ioprio
 };
@@ -1066,8 +1064,6 @@ static const match_table_t tokens = {
 	{Opt_quota, "quota"},
 	{Opt_usrquota, "usrquota"},
 	{Opt_barrier, "barrier=%u"},
-	{Opt_extents, "extents"},
-	{Opt_noextents, "noextents"},
 	{Opt_i_version, "i_version"},
 	{Opt_stripe, "stripe=%u"},
 	{Opt_resize, "resize"},
@@ -1115,7 +1111,6 @@ static int parse_options(char *options, struct super_block *sb,
 	int qtype, qfmt;
 	char *qname;
 #endif
-	ext4_fsblk_t last_block;
 
 	if (!options)
 		return 1;
@@ -1445,33 +1440,6 @@ set_qf_format:
 		case Opt_bh:
 			clear_opt(sbi->s_mount_opt, NOBH);
 			break;
-		case Opt_extents:
-			if (!EXT4_HAS_INCOMPAT_FEATURE(sb,
-					EXT4_FEATURE_INCOMPAT_EXTENTS)) {
-				ext4_warning(sb, __func__,
-					"extents feature not enabled "
-					"on this filesystem, use tune2fs");
-				return 0;
-			}
-			set_opt(sbi->s_mount_opt, EXTENTS);
-			break;
-		case Opt_noextents:
-			/*
-			 * When e2fsprogs support resizing an already existing
-			 * ext3 file system to greater than 2**32 we need to
-			 * add support to block allocator to handle growing
-			 * already existing block  mapped inode so that blocks
-			 * allocated for them fall within 2**32
-			 */
-			last_block = ext4_blocks_count(sbi->s_es) - 1;
-			if (last_block  > 0xffffffffULL) {
-				printk(KERN_ERR "EXT4-fs: Filesystem too "
-						"large to mount with "
-						"-o noextents options\n");
-				return 0;
-			}
-			clear_opt(sbi->s_mount_opt, EXTENTS);
-			break;
 		case Opt_i_version:
 			set_opt(sbi->s_mount_opt, I_VERSION);
 			sb->s_flags |= MS_I_VERSION;
@@ -2135,18 +2103,6 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
 	set_opt(sbi->s_mount_opt, RESERVATION);
 	set_opt(sbi->s_mount_opt, BARRIER);
 
-	/*
-	 * turn on extents feature by default in ext4 filesystem
-	 * only if feature flag already set by mkfs or tune2fs.
-	 * Use -o noextents to turn it off
-	 */
-	if (EXT4_HAS_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_EXTENTS))
-		set_opt(sbi->s_mount_opt, EXTENTS);
-	else
-		ext4_warning(sb, __func__,
-			"extents feature not enabled on this filesystem, "
-			"use tune2fs.");
-
 	/*
 	 * enable delayed allocation by default
 	 * Use -o nodelalloc to turn it off
@@ -3825,7 +3781,7 @@ static void __exit exit_ext4_fs(void)
 }
 
 MODULE_AUTHOR("Remy Card, Stephen Tweedie, Andrew Morton, Andreas Dilger, Theodore Ts'o and others");
-MODULE_DESCRIPTION("Fourth Extended Filesystem with extents");
+MODULE_DESCRIPTION("Fourth Extended Filesystem");
 MODULE_LICENSE("GPL");
 module_init(init_ext4_fs)
 module_exit(exit_ext4_fs)