fat: ->i_pos race fix

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

diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index 0da04e6d1e34b81b7e7adacc6bea9852c6748940..bdd8fb7be2ca48e5ac4e49b5b2dd147375f6c8b2 100644 (file)
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -64,7 +64,7 @@ static inline int __fat_get_block(struct inode *inode, sector_t iblock,
        sector_t phys;
        int err, offset;
 
-       err = fat_bmap(inode, iblock, &phys, &mapped_blocks);
+       err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create);
        if (err)
                return err;
        if (phys) {
@@ -94,7 +94,7 @@ static inline int __fat_get_block(struct inode *inode, sector_t iblock,
        *max_blocks = min(mapped_blocks, *max_blocks);
        MSDOS_I(inode)->mmu_private += *max_blocks << sb->s_blocksize_bits;
 
-       err = fat_bmap(inode, iblock, &phys, &mapped_blocks);
+       err = fat_bmap(inode, iblock, &phys, &mapped_blocks, create);
        if (err)
                return err;
 
@@ -199,7 +199,14 @@ static ssize_t fat_direct_IO(int rw, struct kiocb *iocb,
 
 static sector_t _fat_bmap(struct address_space *mapping, sector_t block)
 {
-       return generic_block_bmap(mapping, block, fat_get_block);
+       sector_t blocknr;
+
+       /* fat_get_cluster() assumes the requested blocknr isn't truncated. */
+       mutex_lock(&mapping->host->i_mutex);
+       blocknr = generic_block_bmap(mapping, block, fat_get_block);
+       mutex_unlock(&mapping->host->i_mutex);
+
+       return blocknr;
 }
 
 static const struct address_space_operations fat_aops = {
@@ -535,6 +542,20 @@ static int fat_statfs(struct dentry *dentry, struct kstatfs *buf)
        return 0;
 }
 
+static inline loff_t fat_i_pos_read(struct msdos_sb_info *sbi,
+                                   struct inode *inode)
+{
+       loff_t i_pos;
+#if BITS_PER_LONG == 32
+       spin_lock(&sbi->inode_hash_lock);
+#endif
+       i_pos = MSDOS_I(inode)->i_pos;
+#if BITS_PER_LONG == 32
+       spin_unlock(&sbi->inode_hash_lock);
+#endif
+       return i_pos;
+}
+
 static int fat_write_inode(struct inode *inode, int wait)
 {
        struct super_block *sb = inode->i_sb;
@@ -544,9 +565,12 @@ static int fat_write_inode(struct inode *inode, int wait)
        loff_t i_pos;
        int err;
 
+       if (inode->i_ino == MSDOS_ROOT_INO)
+               return 0;
+
 retry:
-       i_pos = MSDOS_I(inode)->i_pos;
-       if (inode->i_ino == MSDOS_ROOT_INO || !i_pos)
+       i_pos = fat_i_pos_read(sbi, inode);
+       if (!i_pos)
                return 0;
 
        bh = sb_bread(sb, i_pos >> sbi->dir_per_block_bits);