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>

diff --git a/Documentation/filesystems/vfat.txt b/Documentation/filesystems/vfat.txt
index 3a5ddc9..7d41c0d 100644 (file)
--- a/Documentation/filesystems/vfat.txt
+++ b/Documentation/filesystems/vfat.txt
@@ -132,6 +132,11 @@ rodir            -- FAT has the ATTR_RO (read-only) attribute. But on Windows,
                 If you want to use ATTR_RO as read-only flag even for
                 the directory, set this option.
 
+errors=panic|continue|remount-ro
+             -- specify FAT behavior on critical errors: panic, continue
+                without doing anything or remount the partition in
+                read-only mode (default behavior).
+
 <bool>: 0,1,yes,no,true,false
 
 TODO

diff --git a/fs/fat/cache.c b/fs/fat/cache.c
index b426022..923990e 100644 (file)
--- 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 3a7f603..7e7924c 100644 (file)
--- 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 ea440d6..ed10896 100644 (file)
--- 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 da6eea4..60c31f7 100644 (file)
--- 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 0a7f4a9..6214287 100644 (file)
--- 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 296785a..2b90522 100644 (file)
--- 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 ac39ebc..a6c2047 100644 (file)
--- 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 da3f361..72f5c64 100644 (file)
--- 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 a0e00e3..cb6ddb8 100644 (file)
--- 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);
        }