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Commit a13fb1a4 authored by Eric Sandeen's avatar Eric Sandeen Committed by Theodore Ts'o
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ext4: Add feature set check helper for mount & remount paths 



A user reported that although his root ext4 filesystem was mounting
fine, other filesystems would not mount, with the:

"Filesystem with huge files cannot be mounted RDWR without CONFIG_LBDAF"

error on his 32-bit box built without CONFIG_LBDAF.  This is because
the test at mount time for this situation was not being re-checked
on remount, and the normal boot process makes an ro->rw transition,
so this was being missed.

Refactor to make a common helper function to test the filesystem
features against the type of mount request (RO vs. RW) so that we 
stay consistent.

Addresses Red-Hat-Bugzilla: #517650

Signed-off-by: default avatarEric Sandeen <sandeen@redhat.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 38877f4e

fs/ext4/super.c

+49 −42
Original line number Diff line number Diff line
@@ -2254,6 +2254,49 @@ static struct kobj_type ext4_ktype = { 
	.release	= ext4_sb_release,

};



/*

 * Check whether this filesystem can be mounted based on

 * the features present and the RDONLY/RDWR mount requested.

 * Returns 1 if this filesystem can be mounted as requested,

 * 0 if it cannot be.

 */

static int ext4_feature_set_ok(struct super_block *sb, int readonly)

{

	if (EXT4_HAS_INCOMPAT_FEATURE(sb, ~EXT4_FEATURE_INCOMPAT_SUPP)) {

		ext4_msg(sb, KERN_ERR,

			"Couldn't mount because of "

			"unsupported optional features (%x)",

			(le32_to_cpu(EXT4_SB(sb)->s_es->s_feature_incompat) &

			~EXT4_FEATURE_INCOMPAT_SUPP));

		return 0;

	}



	if (readonly)

		return 1;



	/* Check that feature set is OK for a read-write mount */

	if (EXT4_HAS_RO_COMPAT_FEATURE(sb, ~EXT4_FEATURE_RO_COMPAT_SUPP)) {

		ext4_msg(sb, KERN_ERR, "couldn't mount RDWR because of "

			 "unsupported optional features (%x)",

			 (le32_to_cpu(EXT4_SB(sb)->s_es->s_feature_ro_compat) &

				~EXT4_FEATURE_RO_COMPAT_SUPP));

		return 0;

	}

	/*

	 * Large file size enabled file system can only be mounted

	 * read-write on 32-bit systems if kernel is built with CONFIG_LBDAF

	 */

	if (EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_HUGE_FILE)) {

		if (sizeof(blkcnt_t) < sizeof(u64)) {

			ext4_msg(sb, KERN_ERR, "Filesystem with huge files "

				 "cannot be mounted RDWR without "

				 "CONFIG_LBDAF");

			return 0;

		}

	}

	return 1;

}



static int ext4_fill_super(struct super_block *sb, void *data, int silent)

				__releases(kernel_lock)

				__acquires(kernel_lock)
@@ -2275,7 +2318,6 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) 
	unsigned int db_count;

	unsigned int i;

	int needs_recovery, has_huge_files;

	int features;

	__u64 blocks_count;

	int err;

	unsigned int journal_ioprio = DEFAULT_JOURNAL_IOPRIO;
@@ -2402,39 +2444,9 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) 
	 * previously didn't change the revision level when setting the flags,

	 * so there is a chance incompat flags are set on a rev 0 filesystem.

	 */

	features = EXT4_HAS_INCOMPAT_FEATURE(sb, ~EXT4_FEATURE_INCOMPAT_SUPP);

	if (features) {

		ext4_msg(sb, KERN_ERR,

			"Couldn't mount because of "

			"unsupported optional features (%x)",

			(le32_to_cpu(EXT4_SB(sb)->s_es->s_feature_incompat) &

			~EXT4_FEATURE_INCOMPAT_SUPP));

		goto failed_mount;

	}

	features = EXT4_HAS_RO_COMPAT_FEATURE(sb, ~EXT4_FEATURE_RO_COMPAT_SUPP);

	if (!(sb->s_flags & MS_RDONLY) && features) {

		ext4_msg(sb, KERN_ERR,

			"Couldn't mount RDWR because of "

			"unsupported optional features (%x)",

			(le32_to_cpu(EXT4_SB(sb)->s_es->s_feature_ro_compat) &

			~EXT4_FEATURE_RO_COMPAT_SUPP));

	if (!ext4_feature_set_ok(sb, (sb->s_flags & MS_RDONLY)))

		goto failed_mount;

	}

	has_huge_files = EXT4_HAS_RO_COMPAT_FEATURE(sb,

				    EXT4_FEATURE_RO_COMPAT_HUGE_FILE);

	if (has_huge_files) {

		/*

		 * Large file size enabled file system can only be

		 * mount if kernel is build with CONFIG_LBDAF

		 */

		if (sizeof(root->i_blocks) < sizeof(u64) &&

				!(sb->s_flags & MS_RDONLY)) {

			ext4_msg(sb, KERN_ERR, "Filesystem with huge "

					"files cannot be mounted read-write "

					"without CONFIG_LBDAF");

			goto failed_mount;

		}

	}



	blocksize = BLOCK_SIZE << le32_to_cpu(es->s_log_block_size);



	if (blocksize < EXT4_MIN_BLOCK_SIZE ||
@@ -2470,6 +2482,8 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) 
		}

	}



	has_huge_files = EXT4_HAS_RO_COMPAT_FEATURE(sb,

				EXT4_FEATURE_RO_COMPAT_HUGE_FILE);

	sbi->s_bitmap_maxbytes = ext4_max_bitmap_size(sb->s_blocksize_bits,

						      has_huge_files);

	sb->s_maxbytes = ext4_max_size(sb->s_blocksize_bits, has_huge_files);
@@ -3485,18 +3499,11 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data) 
			if (sbi->s_journal)

				ext4_mark_recovery_complete(sb, es);

		} else {

			int ret;

			if ((ret = EXT4_HAS_RO_COMPAT_FEATURE(sb,

					~EXT4_FEATURE_RO_COMPAT_SUPP))) {

				ext4_msg(sb, KERN_WARNING, "couldn't "

				       "remount RDWR because of unsupported "

				       "optional features (%x)",

				(le32_to_cpu(sbi->s_es->s_feature_ro_compat) &

					~EXT4_FEATURE_RO_COMPAT_SUPP));

			/* Make sure we can mount this feature set readwrite */

			if (!ext4_feature_set_ok(sb, 0)) {

				err = -EROFS;

				goto restore_opts;

			}



			/*

			 * Make sure the group descriptor checksums

			 * are sane.  If they aren't, refuse to remount r/w.