[11/90] ext4: Add feature set check helper for mount & remount paths

Greg KH
2009-12-11T04:36:13Z

[-- Attachment #1: 0011-ext4-Add-feature-set-check-helper-for-mount-remount-.patch --]
[-- Type: text/plain, Size: 5484 bytes --]

2.6.31-stable review patch. If anyone has any objections, please let us know.

------------------
(cherry picked from commit a13fb1a4533f26c1e2b0204d5283b696689645af)

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: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---
fs/ext4/super.c | 91 ++++++++++++++++++++++++++++++--------------------------
1 file changed, 49 insertions(+), 42 deletions(-)

--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -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_
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_
* 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));
+ if (!ext4_feature_set_ok(sb, (sb->s_flags & MS_RDONLY)))
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));
- 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_
}
}

+ 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_blo
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.