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Commit cbdf5a24 authored by David Woodhouse's avatar David Woodhouse Committed by Chris Mason
Browse files

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: default avatarDavid Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent be6e8dc0

fs/btrfs/inode.c

+102 −2
Original line number Diff line number Diff line
@@ -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 @@ static int btrfs_readdir(struct file *filp, void *dirent, filldir_t filldir) 
	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,