fat: mmu_private race fix

[linux-2.6-omap-h63xx.git] / fs / fat / fat.h

diff --git a/fs/fat/fat.h b/fs/fat/fat.h
index 3b4753a024e3ef791cbd95b4a6d6cf1d432557d3..4efc5038ed29b310205c680e12e75de76161dc46 100644 (file)
--- a/fs/fat/fat.h
+++ b/fs/fat/fat.h
@@ -38,7 +38,8 @@ struct fat_mount_options {
                 flush:1,         /* write things quickly */
                 nocase:1,        /* Does this need case conversion? 0=need case conversion*/
                 usefree:1,       /* Use free_clusters for FAT32 */
-                tz_utc:1;        /* Filesystem timestamps are in UTC */
+                tz_utc:1,        /* Filesystem timestamps are in UTC */
+                rodir:1;         /* allow ATTR_RO for directory */
 };
 
 #define FAT_HASH_BITS  8
@@ -90,7 +91,9 @@ struct msdos_inode_info {
        /* for avoiding the race between fat_free() and fat_get_cluster() */
        unsigned int cache_valid_id;
 
-       loff_t mmu_private;
+       /* NOTE: mmu_private is 64bits, so must hold ->i_mutex to access */
+       loff_t mmu_private;     /* physically allocated size */
+
        int i_start;            /* first cluster or 0 */
        int i_logstart;         /* logical first cluster */
        int i_attrs;            /* unused attribute bits */
@@ -117,11 +120,35 @@ static inline struct msdos_inode_info *MSDOS_I(struct inode *inode)
        return container_of(inode, struct msdos_inode_info, vfs_inode);
 }
 
+/*
+ * If ->i_mode can't hold S_IWUGO (i.e. ATTR_RO), we use ->i_attrs to
+ * save ATTR_RO instead of ->i_mode.
+ *
+ * If it's directory and !sbi->options.rodir, ATTR_RO isn't read-only
+ * bit, it's just used as flag for app.
+ */
+static inline int fat_mode_can_hold_ro(struct inode *inode)
+{
+       struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
+       mode_t mask;
+
+       if (S_ISDIR(inode->i_mode)) {
+               if (!sbi->options.rodir)
+                       return 0;
+               mask = ~sbi->options.fs_dmask;
+       } else
+               mask = ~sbi->options.fs_fmask;
+
+       if (!(mask & S_IWUGO))
+               return 0;
+       return 1;
+}
+
 /* Convert attribute bits and a mask to the UNIX mode. */
 static inline mode_t fat_make_mode(struct msdos_sb_info *sbi,
                                   u8 attrs, mode_t mode)
 {
-       if (attrs & ATTR_RO)
+       if (attrs & ATTR_RO && !((attrs & ATTR_DIR) && !sbi->options.rodir))
                mode &= ~S_IWUGO;
 
        if (attrs & ATTR_DIR)
@@ -133,14 +160,20 @@ static inline mode_t fat_make_mode(struct msdos_sb_info *sbi,
 /* Return the FAT attribute byte for this inode */
 static inline u8 fat_make_attrs(struct inode *inode)
 {
-       return ((inode->i_mode & S_IWUGO) ? ATTR_NONE : ATTR_RO) |
-               (S_ISDIR(inode->i_mode) ? ATTR_DIR : ATTR_NONE) |
-               MSDOS_I(inode)->i_attrs;
+       u8 attrs = MSDOS_I(inode)->i_attrs;
+       if (S_ISDIR(inode->i_mode))
+               attrs |= ATTR_DIR;
+       if (fat_mode_can_hold_ro(inode) && !(inode->i_mode & S_IWUGO))
+               attrs |= ATTR_RO;
+       return attrs;
 }
 
 static inline void fat_save_attrs(struct inode *inode, u8 attrs)
 {
-       MSDOS_I(inode)->i_attrs = attrs & ATTR_UNUSED;
+       if (fat_mode_can_hold_ro(inode))
+               MSDOS_I(inode)->i_attrs = attrs & ATTR_UNUSED;
+       else
+               MSDOS_I(inode)->i_attrs = attrs & (ATTR_UNUSED | ATTR_RO);
 }
 
 static inline unsigned char fat_checksum(const __u8 *name)
@@ -191,7 +224,7 @@ extern void fat_cache_inval_inode(struct inode *inode);
 extern int fat_get_cluster(struct inode *inode, int cluster,
                           int *fclus, int *dclus);
 extern int fat_bmap(struct inode *inode, sector_t sector, sector_t *phys,
-                   unsigned long *mapped_blocks);
+                   unsigned long *mapped_blocks, int create);
 
 /* fat/dir.c */
 extern const struct file_operations fat_dir_operations;
@@ -277,7 +310,8 @@ 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_panic(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);
 extern void fat_time_fat2unix(struct msdos_sb_info *sbi, struct timespec *ts,