FAT: add 'errors' mount option

On severe errors FAT remounts itself in read-only mode. Allow to
specify FAT fs desired behavior through 'errors' mount option:
panic, continue or remount read-only.

`mount -t [fat|vfat] -o errors=[panic,remount-ro,continue] \
	<bdev> <mount point>`

This is analog to ext2 fs 'errors' mount option.

Signed-off-by: Denis Karpov <ext-denis.2.karpov@nokia.com>
Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>

1 files changed, 14 insertions, 8 deletions

diff --git a/fs/fat/misc.c b/fs/fat/misc.c
index ac39ebcc1496..a6c20473dfd7 100644
--- a/fs/fat/misc.c
+++ b/fs/fat/misc.c
@@ -12,14 +12,19 @@
 #include "fat.h"
 
 /*
- * fat_fs_panic reports a severe file system problem and sets the file system
- * read-only. The file system can be made writable again by remounting it.
+ * fat_fs_error reports a file system problem that might indicate fa data
+ * corruption/inconsistency. Depending on 'errors' mount option the
+ * panic() is called, or error message is printed FAT and nothing is done,
+ * or filesystem is remounted read-only (default behavior).
+ * In case the file system is remounted read-only, it can be made writable
+ * again by remounting it.
  */
-void fat_fs_panic(struct super_block *s, const char *fmt, ...)
+void fat_fs_error(struct super_block *s, const char *fmt, ...)
 {
+	struct fat_mount_options *opts = &MSDOS_SB(s)->options;
 	va_list args;
 
-	printk(KERN_ERR "FAT: Filesystem panic (dev %s)\n", s->s_id);
+	printk(KERN_ERR "FAT: Filesystem error (dev %s)\n", s->s_id);
 
 	printk(KERN_ERR "    ");
 	va_start(args, fmt);
@@ -27,13 +32,14 @@ void fat_fs_panic(struct super_block *s, const char *fmt, ...)
 	va_end(args);
 	printk("\n");
 
-	if (!(s->s_flags & MS_RDONLY)) {
+	if (opts->errors == FAT_ERRORS_PANIC)
+		panic("    FAT fs panic from previous error\n");
+	else if (opts->errors == FAT_ERRORS_RO && !(s->s_flags & MS_RDONLY)) {
 		s->s_flags |= MS_RDONLY;
 		printk(KERN_ERR "    File system has been set read-only\n");
 	}
 }
-
-EXPORT_SYMBOL_GPL(fat_fs_panic);
+EXPORT_SYMBOL_GPL(fat_fs_error);
 
 /* Flushes the number of free clusters on FAT32 */
 /* XXX: Need to write one per FSINFO block.  Currently only writes 1 */
@@ -124,7 +130,7 @@ int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster)
 			mark_inode_dirty(inode);
 	}
 	if (new_fclus != (inode->i_blocks >> (sbi->cluster_bits - 9))) {
-		fat_fs_panic(sb, "clusters badly computed (%d != %llu)",
+		fat_fs_error(sb, "clusters badly computed (%d != %llu)",
 			     new_fclus,
 			     (llu)(inode->i_blocks >> (sbi->cluster_bits - 9)));
 		fat_cache_inval_inode(inode);