1 files changed, 49 insertions, 42 deletions

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index de67c3657b83..4037fe0b5a5c 100644
--- 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_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.