From cbdf5a2442330102c08f5a2ad3058e29e90a43a9 Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Wed, 6 Aug 2008 19:42:33 +0100 Subject: [PATCH] Btrfs: Implement our own copy of the nfsd readdir hack, for older kernels Date: Wed, 6 Aug 2008 19:42:33 +0100 Signed-off-by: David Woodhouse Signed-off-by: Chris Mason --- fs/btrfs/inode.c | 104 ++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 102 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 266ca5514b33..0da1ae4ee407 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -1915,7 +1915,8 @@ static unsigned char btrfs_filetype_table[] = { DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK }; -static int btrfs_readdir(struct file *filp, void *dirent, filldir_t filldir) +static int btrfs_real_readdir(struct file *filp, void *dirent, + filldir_t filldir) { struct inode *inode = filp->f_dentry->d_inode; struct btrfs_root *root = BTRFS_I(inode)->root; @@ -2064,6 +2065,101 @@ err: return ret; } +/* Kernels earlier than 2.6.28 still have the NFS deadlock where nfsd + will call the file system's ->lookup() method from within its + filldir callback, which in turn was called from the file system's + ->readdir() method. And will deadlock for many file systems. */ +#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,28) + +struct nfshack_dirent { + u64 ino; + loff_t offset; + int namlen; + unsigned int d_type; + char name[]; +}; + +struct nfshack_readdir { + char *dirent; + size_t used; +}; + + + +static int btrfs_nfshack_filldir(void *__buf, const char *name, int namlen, + loff_t offset, u64 ino, unsigned int d_type) +{ + struct nfshack_readdir *buf = __buf; + struct nfshack_dirent *de = (void *)(buf->dirent + buf->used); + unsigned int reclen; + + reclen = ALIGN(sizeof(struct nfshack_dirent) + namlen, sizeof(u64)); + if (buf->used + reclen > PAGE_SIZE) + return -EINVAL; + + de->namlen = namlen; + de->offset = offset; + de->ino = ino; + de->d_type = d_type; + memcpy(de->name, name, namlen); + buf->used += reclen; + + return 0; +} + +static int btrfs_nfshack_readdir(struct file *file, void *dirent, + filldir_t filldir) +{ + struct nfshack_readdir buf; + struct nfshack_dirent *de; + int err; + int size; + loff_t offset; + + buf.dirent = (void *)__get_free_page(GFP_KERNEL); + if (!buf.dirent) + return -ENOMEM; + + offset = file->f_pos; + + while (1) { + unsigned int reclen; + + buf.used = 0; + + err = btrfs_real_readdir(file, &buf, btrfs_nfshack_filldir); + if (err) + break; + + size = buf.used; + + if (!size) + break; + + de = (struct nfshack_dirent *)buf.dirent; + while (size > 0) { + offset = de->offset; + + if (filldir(dirent, de->name, de->namlen, de->offset, + de->ino, de->d_type)) + goto done; + offset = file->f_pos; + + reclen = ALIGN(sizeof(*de) + de->namlen, + sizeof(u64)); + size -= reclen; + de = (struct nfshack_dirent *)((char *)de + reclen); + } + } + + done: + free_page((unsigned long)buf.dirent); + file->f_pos = offset; + + return err; +} +#endif + int btrfs_write_inode(struct inode *inode, int wait) { struct btrfs_root *root = BTRFS_I(inode)->root; @@ -3623,7 +3719,11 @@ static struct inode_operations btrfs_dir_ro_inode_operations = { static struct file_operations btrfs_dir_file_operations = { .llseek = generic_file_llseek, .read = generic_read_dir, - .readdir = btrfs_readdir, +#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,28) + .readdir = btrfs_nfshack_readdir, +#else /* NFSd readdir/lookup deadlock is fixed */ + .readdir = btrfs_real_readdir, +#endif .unlocked_ioctl = btrfs_ioctl, #ifdef CONFIG_COMPAT .compat_ioctl = btrfs_ioctl, -- 2.30.2