From 9ca59f4c3d28df14a1545a1e2832f34a0a50e3ed Mon Sep 17 00:00:00 2001 From: OGAWA Hirofumi Date: Thu, 6 Nov 2008 12:53:57 -0800 Subject: [PATCH] fat: ->i_pos race fix i_pos is 64bits value, hence it's not atomic to update. Important place is fat_write_inode() only, other places without lock are just for printk(). This adds lock for "BITS_PER_LONG == 32" kernel. Signed-off-by: OGAWA Hirofumi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/fat/inode.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) diff --git a/fs/fat/inode.c b/fs/fat/inode.c index 9e37ad93c73..bdd8fb7be2c 100644 --- a/fs/fat/inode.c +++ b/fs/fat/inode.c @@ -542,6 +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; @@ -551,9 +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); -- 2.20.1