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-rw-r--r--fs/fat/fat.h33
1 files changed, 29 insertions, 4 deletions
diff --git a/fs/fat/fat.h b/fs/fat/fat.h
index 3b4753a..313b645 100644
--- a/fs/fat/fat.h
+++ b/fs/fat/fat.h
@@ -117,6 +117,25 @@ 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.
+ */
+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))
+ 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)
@@ -133,14 +152,20 @@ 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)
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