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>

9 files changed, 53 insertions, 22 deletions

diff --git a/fs/fat/cache.c b/fs/fat/cache.c
index b4260229808..923990e4f16 100644
--- a/fs/fat/cache.c
+++ b/fs/fat/cache.c
@@ -241,7 +241,7 @@ int fat_get_cluster(struct inode *inode, int cluster, int *fclus, int *dclus)
         while (*fclus < cluster) {
                 /* prevent the infinite loop of cluster chain */
                 if (*fclus > limit) {
-                        fat_fs_panic(sb, "%s: detected the cluster chain loop"
+                        fat_fs_error(sb, "%s: detected the cluster chain loop"
                                      " (i_pos %lld)", __func__,
                                      MSDOS_I(inode)->i_pos);
                         nr = -EIO;
@@ -252,7 +252,7 @@ int fat_get_cluster(struct inode *inode, int cluster, int *fclus, int *dclus)
                 if (nr < 0)
                         goto out;
                 else if (nr == FAT_ENT_FREE) {
-                        fat_fs_panic(sb, "%s: invalid cluster chain"
+                        fat_fs_error(sb, "%s: invalid cluster chain"
                                      " (i_pos %lld)", __func__,
                                      MSDOS_I(inode)->i_pos);
                         nr = -EIO;
@@ -285,7 +285,7 @@ static int fat_bmap_cluster(struct inode *inode, int cluster)
         if (ret < 0)
                 return ret;
         else if (ret == FAT_ENT_EOF) {
-                fat_fs_panic(sb, "%s: request beyond EOF (i_pos %lld)",
+                fat_fs_error(sb, "%s: request beyond EOF (i_pos %lld)",
                              __func__, MSDOS_I(inode)->i_pos);
                 return -EIO;
         }
diff --git a/fs/fat/dir.c b/fs/fat/dir.c
index 3a7f603b698..7e7924c2ea3 100644
--- a/fs/fat/dir.c
+++ b/fs/fat/dir.c
@@ -1334,7 +1334,7 @@ found:
                         goto error_remove;
                 }
                 if (dir->i_size & (sbi->cluster_size - 1)) {
-                        fat_fs_panic(sb, "Odd directory size");
+                        fat_fs_error(sb, "Odd directory size");
                         dir->i_size = (dir->i_size + sbi->cluster_size - 1)
                                 & ~((loff_t)sbi->cluster_size - 1);
                 }
diff --git a/fs/fat/fat.h b/fs/fat/fat.h
index ea440d65819..ed10896d5da 100644
--- a/fs/fat/fat.h
+++ b/fs/fat/fat.h
@@ -17,6 +17,10 @@
 #define VFAT_SFN_CREATE_WIN95   0x0100 /* emulate win95 rule for create */
 #define VFAT_SFN_CREATE_WINNT   0x0200 /* emulate winnt rule for create */
 
+#define FAT_ERRORS_CONT         1      /* ignore error and continue */
+#define FAT_ERRORS_PANIC        2      /* panic on error */
+#define FAT_ERRORS_RO           3      /* remount r/o on error */
+
 struct fat_mount_options {
         uid_t fs_uid;
         gid_t fs_gid;
@@ -26,6 +30,7 @@ struct fat_mount_options {
         char *iocharset;          /* Charset used for filename input/display */
         unsigned short shortname; /* flags for shortname display/create rule */
         unsigned char name_check; /* r = relaxed, n = normal, s = strict */
+        unsigned char errors;     /* On error: continue, panic, remount-ro */
         unsigned short allow_utime;/* permission for setting the [am]time */
         unsigned quiet:1,         /* set = fake successful chmods and chowns */
                  showexec:1,      /* set = only set x bit for com/exe/bat */
@@ -310,7 +315,7 @@ extern int fat_fill_super(struct super_block *sb, void *data, int silent,
 extern int fat_flush_inodes(struct super_block *sb, struct inode *i1,
                             struct inode *i2);
 /* fat/misc.c */
-extern void fat_fs_panic(struct super_block *s, const char *fmt, ...)
+extern void fat_fs_error(struct super_block *s, const char *fmt, ...)
         __attribute__ ((format (printf, 2, 3))) __cold;
 extern void fat_clusters_flush(struct super_block *sb);
 extern int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster);
diff --git a/fs/fat/fatent.c b/fs/fat/fatent.c
index da6eea47872..60c31f7e678 100644
--- a/fs/fat/fatent.c
+++ b/fs/fat/fatent.c
@@ -345,7 +345,7 @@ int fat_ent_read(struct inode *inode, struct fat_entry *fatent, int entry)
 
         if (entry < FAT_START_ENT || sbi->max_cluster <= entry) {
                 fatent_brelse(fatent);
-                fat_fs_panic(sb, "invalid access to FAT (entry 0x%08x)", entry);
+                fat_fs_error(sb, "invalid access to FAT (entry 0x%08x)", entry);
                 return -EIO;
         }
 
@@ -557,7 +557,7 @@ int fat_free_clusters(struct inode *inode, int cluster)
                         err = cluster;
                         goto error;
                 } else if (cluster == FAT_ENT_FREE) {
-                        fat_fs_panic(sb, "%s: deleting FAT entry beyond EOF",
+                        fat_fs_error(sb, "%s: deleting FAT entry beyond EOF",
                                      __func__);
                         err = -EIO;
                         goto error;
diff --git a/fs/fat/file.c b/fs/fat/file.c
index 0a7f4a9918b..6214287210f 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -213,7 +213,7 @@ static int fat_free(struct inode *inode, int skip)
                         fatent_brelse(&fatent);
                         return 0;
                 } else if (ret == FAT_ENT_FREE) {
-                        fat_fs_panic(sb,
+                        fat_fs_error(sb,
                                      "%s: invalid cluster chain (i_pos %lld)",
                                      __func__, MSDOS_I(inode)->i_pos);
                         ret = -EIO;
diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index 296785a0dec..2b9052265e3 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -76,7 +76,7 @@ static inline int __fat_get_block(struct inode *inode, sector_t iblock,
                 return 0;
 
         if (iblock != MSDOS_I(inode)->mmu_private >> sb->s_blocksize_bits) {
-                fat_fs_panic(sb, "corrupted file size (i_pos %lld, %lld)",
+                fat_fs_error(sb, "corrupted file size (i_pos %lld, %lld)",
                         MSDOS_I(inode)->i_pos, MSDOS_I(inode)->mmu_private);
                 return -EIO;
         }
@@ -834,6 +834,12 @@ static int fat_show_options(struct seq_file *m, struct vfsmount *mnt)
                 seq_puts(m, ",flush");
         if (opts->tz_utc)
                 seq_puts(m, ",tz=UTC");
+        if (opts->errors == FAT_ERRORS_CONT)
+                seq_puts(m, ",errors=continue");
+        else if (opts->errors == FAT_ERRORS_PANIC)
+                seq_puts(m, ",errors=panic");
+        else
+                seq_puts(m, ",errors=remount-ro");
 
         return 0;
 }
@@ -846,7 +852,8 @@ enum {
         Opt_charset, Opt_shortname_lower, Opt_shortname_win95,
         Opt_shortname_winnt, Opt_shortname_mixed, Opt_utf8_no, Opt_utf8_yes,
         Opt_uni_xl_no, Opt_uni_xl_yes, Opt_nonumtail_no, Opt_nonumtail_yes,
-        Opt_obsolate, Opt_flush, Opt_tz_utc, Opt_rodir, Opt_err,
+        Opt_obsolate, Opt_flush, Opt_tz_utc, Opt_rodir, Opt_err_cont,
+        Opt_err_panic, Opt_err_ro, Opt_err,
 };
 
 static const match_table_t fat_tokens = {
@@ -869,6 +876,11 @@ static const match_table_t fat_tokens = {
         {Opt_showexec, "showexec"},
         {Opt_debug, "debug"},
         {Opt_immutable, "sys_immutable"},
+        {Opt_flush, "flush"},
+        {Opt_tz_utc, "tz=UTC"},
+        {Opt_err_cont, "errors=continue"},
+        {Opt_err_panic, "errors=panic"},
+        {Opt_err_ro, "errors=remount-ro"},
         {Opt_obsolate, "conv=binary"},
         {Opt_obsolate, "conv=text"},
         {Opt_obsolate, "conv=auto"},
@@ -880,8 +892,6 @@ static const match_table_t fat_tokens = {
         {Opt_obsolate, "cvf_format=%20s"},
         {Opt_obsolate, "cvf_options=%100s"},
         {Opt_obsolate, "posix"},
-        {Opt_flush, "flush"},
-        {Opt_tz_utc, "tz=UTC"},
         {Opt_err, NULL},
 };
 static const match_table_t msdos_tokens = {
@@ -951,6 +961,7 @@ static int parse_options(char *options, int is_vfat, int silent, int *debug,
         opts->numtail = 1;
         opts->usefree = opts->nocase = 0;
         opts->tz_utc = 0;
+        opts->errors = FAT_ERRORS_RO;
         *debug = 0;
 
         if (!options)
@@ -1043,6 +1054,15 @@ static int parse_options(char *options, int is_vfat, int silent, int *debug,
                 case Opt_tz_utc:
                         opts->tz_utc = 1;
                         break;
+                case Opt_err_cont:
+                        opts->errors = FAT_ERRORS_CONT;
+                        break;
+                case Opt_err_panic:
+                        opts->errors = FAT_ERRORS_PANIC;
+                        break;
+                case Opt_err_ro:
+                        opts->errors = FAT_ERRORS_RO;
+                        break;
 
                 /* msdos specific */
                 case Opt_dots:
diff --git a/fs/fat/misc.c b/fs/fat/misc.c
index ac39ebcc149..a6c20473dfd 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);
diff --git a/fs/fat/namei_msdos.c b/fs/fat/namei_msdos.c
index da3f361a37d..72f5c6402ef 100644
--- a/fs/fat/namei_msdos.c
+++ b/fs/fat/namei_msdos.c
@@ -608,7 +608,7 @@ error_inode:
                 sinfo.bh = NULL;
         }
         if (corrupt < 0) {
-                fat_fs_panic(new_dir->i_sb,
+                fat_fs_error(new_dir->i_sb,
                              "%s: Filesystem corrupted (i_pos %lld)",
                              __func__, sinfo.i_pos);
         }
diff --git a/fs/fat/namei_vfat.c b/fs/fat/namei_vfat.c
index a0e00e3a46e..cb6ddb8c0bc 100644
--- a/fs/fat/namei_vfat.c
+++ b/fs/fat/namei_vfat.c
@@ -1030,7 +1030,7 @@ error_inode:
                 sinfo.bh = NULL;
         }
         if (corrupt < 0) {
-                fat_fs_panic(new_dir->i_sb,
+                fat_fs_error(new_dir->i_sb,
                              "%s: Filesystem corrupted (i_pos %lld)",
                              __func__, sinfo.i_pos);
         }