fat: Update free_clusters even if it is untrusted
OGAWA Hirofumi [Mon, 28 Apr 2008 09:16:27 +0000 (02:16 -0700)]
Currently, free_clusters is not updated until it is trusted, because
Windows doesn't update it correctly.

But if user is using FAT driver of Linux, it updates free_clusters
correctly.  Instead, this updates it even if it's untrusted, so if
free_clustes is correct, now keep correct value.

Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/fat/fatent.c
fs/fat/inode.c
include/linux/msdos_fs.h

index 5fb3669..c7c8ab2 100644 (file)
@@ -450,7 +450,8 @@ int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster)
        BUG_ON(nr_cluster > (MAX_BUF_PER_PAGE / 2));    /* fixed limit */
 
        lock_fat(sbi);
-       if (sbi->free_clusters != -1 && sbi->free_clusters < nr_cluster) {
+       if (sbi->free_clusters != -1 && sbi->free_clus_valid &&
+           sbi->free_clusters < nr_cluster) {
                unlock_fat(sbi);
                return -ENOSPC;
        }
@@ -504,6 +505,7 @@ int fat_alloc_clusters(struct inode *inode, int *cluster, int nr_cluster)
 
        /* Couldn't allocate the free entries */
        sbi->free_clusters = 0;
+       sbi->free_clus_valid = 1;
        sb->s_dirt = 1;
        err = -ENOSPC;
 
@@ -615,7 +617,7 @@ int fat_count_free_clusters(struct super_block *sb)
        int err = 0, free;
 
        lock_fat(sbi);
-       if (sbi->free_clusters != -1)
+       if (sbi->free_clusters != -1 && sbi->free_clus_valid)
                goto out;
 
        reada_blocks = FAT_READA_SIZE >> sb->s_blocksize_bits;
@@ -643,6 +645,7 @@ int fat_count_free_clusters(struct super_block *sb)
                } while (fat_ent_next(sbi, &fatent));
        }
        sbi->free_clusters = free;
+       sbi->free_clus_valid = 1;
        sb->s_dirt = 1;
        fatent_brelse(&fatent);
 out:
index 886f609..1604a8a 100644 (file)
@@ -537,7 +537,7 @@ static int fat_statfs(struct dentry *dentry, struct kstatfs *buf)
        struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
 
        /* If the count of free cluster is still unknown, counts it here. */
-       if (sbi->free_clusters == -1) {
+       if (sbi->free_clusters == -1 || !sbi->free_clus_valid) {
                int err = fat_count_free_clusters(dentry->d_sb);
                if (err)
                        return err;
@@ -1274,6 +1274,7 @@ int fat_fill_super(struct super_block *sb, void *data, int silent,
        sbi->fat_length = le16_to_cpu(b->fat_length);
        sbi->root_cluster = 0;
        sbi->free_clusters = -1;        /* Don't know yet */
+       sbi->free_clus_valid = 0;
        sbi->prev_free = FAT_START_ENT;
 
        if (!sbi->fat_length && b->fat32_length) {
@@ -1309,8 +1310,8 @@ int fat_fill_super(struct super_block *sb, void *data, int silent,
                               sbi->fsinfo_sector);
                } else {
                        if (sbi->options.usefree)
-                               sbi->free_clusters =
-                                       le32_to_cpu(fsinfo->free_clusters);
+                               sbi->free_clus_valid = 1;
+                       sbi->free_clusters = le32_to_cpu(fsinfo->free_clusters);
                        sbi->prev_free = le32_to_cpu(fsinfo->next_cluster);
                }
 
index 81fb9bc..0bca157 100644 (file)
@@ -233,6 +233,7 @@ struct msdos_sb_info {
        struct mutex fat_lock;
        unsigned int prev_free;      /* previously allocated cluster number */
        unsigned int free_clusters;  /* -1 if undefined */
+       unsigned int free_clus_valid; /* is free_clusters valid? */
        struct fat_mount_options options;
        struct nls_table *nls_disk;  /* Codepage used on disk */
        struct nls_table *nls_io;    /* Charset used for input and display */