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 <David.Woodhouse@intel.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
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be6e8dc0ba
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cbdf5a2442
104
fs/btrfs/inode.c
104
fs/btrfs/inode.c
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@ -1915,7 +1915,8 @@ static unsigned char btrfs_filetype_table[] = {
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DT_UNKNOWN, DT_REG, DT_DIR, DT_CHR, DT_BLK, DT_FIFO, DT_SOCK, DT_LNK
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};
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static int btrfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
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static int btrfs_real_readdir(struct file *filp, void *dirent,
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filldir_t filldir)
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{
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struct inode *inode = filp->f_dentry->d_inode;
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struct btrfs_root *root = BTRFS_I(inode)->root;
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@ -2064,6 +2065,101 @@ err:
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return ret;
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}
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/* Kernels earlier than 2.6.28 still have the NFS deadlock where nfsd
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will call the file system's ->lookup() method from within its
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filldir callback, which in turn was called from the file system's
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->readdir() method. And will deadlock for many file systems. */
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#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,28)
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struct nfshack_dirent {
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u64 ino;
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loff_t offset;
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int namlen;
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unsigned int d_type;
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char name[];
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};
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struct nfshack_readdir {
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char *dirent;
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size_t used;
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};
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static int btrfs_nfshack_filldir(void *__buf, const char *name, int namlen,
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loff_t offset, u64 ino, unsigned int d_type)
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{
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struct nfshack_readdir *buf = __buf;
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struct nfshack_dirent *de = (void *)(buf->dirent + buf->used);
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unsigned int reclen;
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reclen = ALIGN(sizeof(struct nfshack_dirent) + namlen, sizeof(u64));
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if (buf->used + reclen > PAGE_SIZE)
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return -EINVAL;
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de->namlen = namlen;
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de->offset = offset;
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de->ino = ino;
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de->d_type = d_type;
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memcpy(de->name, name, namlen);
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buf->used += reclen;
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return 0;
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}
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static int btrfs_nfshack_readdir(struct file *file, void *dirent,
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filldir_t filldir)
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{
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struct nfshack_readdir buf;
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struct nfshack_dirent *de;
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int err;
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int size;
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loff_t offset;
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buf.dirent = (void *)__get_free_page(GFP_KERNEL);
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if (!buf.dirent)
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return -ENOMEM;
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offset = file->f_pos;
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while (1) {
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unsigned int reclen;
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buf.used = 0;
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err = btrfs_real_readdir(file, &buf, btrfs_nfshack_filldir);
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if (err)
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break;
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size = buf.used;
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if (!size)
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break;
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de = (struct nfshack_dirent *)buf.dirent;
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while (size > 0) {
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offset = de->offset;
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if (filldir(dirent, de->name, de->namlen, de->offset,
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de->ino, de->d_type))
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goto done;
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offset = file->f_pos;
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reclen = ALIGN(sizeof(*de) + de->namlen,
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sizeof(u64));
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size -= reclen;
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de = (struct nfshack_dirent *)((char *)de + reclen);
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}
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}
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done:
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free_page((unsigned long)buf.dirent);
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file->f_pos = offset;
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return err;
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}
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#endif
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int btrfs_write_inode(struct inode *inode, int wait)
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{
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struct btrfs_root *root = BTRFS_I(inode)->root;
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@ -3623,7 +3719,11 @@ static struct inode_operations btrfs_dir_ro_inode_operations = {
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static struct file_operations btrfs_dir_file_operations = {
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.llseek = generic_file_llseek,
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.read = generic_read_dir,
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.readdir = btrfs_readdir,
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#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,28)
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.readdir = btrfs_nfshack_readdir,
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#else /* NFSd readdir/lookup deadlock is fixed */
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.readdir = btrfs_real_readdir,
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#endif
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.unlocked_ioctl = btrfs_ioctl,
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#ifdef CONFIG_COMPAT
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.compat_ioctl = btrfs_ioctl,
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