// SPDX-License-Identifier: GPL-2.0-or-later
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/* AFS filesystem directory editing
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*
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* Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*/
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#include <linux/kernel.h>
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#include <linux/fs.h>
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#include <linux/namei.h>
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#include <linux/pagemap.h>
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#include <linux/iversion.h>
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#include "internal.h"
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#include "xdr_fs.h"
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/*
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* Find a number of contiguous clear bits in a directory block bitmask.
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*
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* There are 64 slots, which means we can load the entire bitmap into a
|
* variable. The first bit doesn't count as it corresponds to the block header
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* slot. nr_slots is between 1 and 9.
|
*/
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static int afs_find_contig_bits(union afs_xdr_dir_block *block, unsigned int nr_slots)
|
{
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u64 bitmap;
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u32 mask;
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int bit, n;
|
|
bitmap = (u64)block->hdr.bitmap[0] << 0 * 8;
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bitmap |= (u64)block->hdr.bitmap[1] << 1 * 8;
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bitmap |= (u64)block->hdr.bitmap[2] << 2 * 8;
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bitmap |= (u64)block->hdr.bitmap[3] << 3 * 8;
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bitmap |= (u64)block->hdr.bitmap[4] << 4 * 8;
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bitmap |= (u64)block->hdr.bitmap[5] << 5 * 8;
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bitmap |= (u64)block->hdr.bitmap[6] << 6 * 8;
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bitmap |= (u64)block->hdr.bitmap[7] << 7 * 8;
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bitmap >>= 1; /* The first entry is metadata */
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bit = 1;
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mask = (1 << nr_slots) - 1;
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do {
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if (sizeof(unsigned long) == 8)
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n = ffz(bitmap);
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else
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n = ((u32)bitmap) != 0 ?
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ffz((u32)bitmap) :
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ffz((u32)(bitmap >> 32)) + 32;
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bitmap >>= n;
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bit += n;
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if ((bitmap & mask) == 0) {
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if (bit > 64 - nr_slots)
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return -1;
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return bit;
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}
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n = __ffs(bitmap);
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bitmap >>= n;
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bit += n;
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} while (bitmap);
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return -1;
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}
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/*
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* Set a number of contiguous bits in the directory block bitmap.
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*/
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static void afs_set_contig_bits(union afs_xdr_dir_block *block,
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int bit, unsigned int nr_slots)
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{
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u64 mask;
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mask = (1 << nr_slots) - 1;
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mask <<= bit;
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block->hdr.bitmap[0] |= (u8)(mask >> 0 * 8);
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block->hdr.bitmap[1] |= (u8)(mask >> 1 * 8);
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block->hdr.bitmap[2] |= (u8)(mask >> 2 * 8);
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block->hdr.bitmap[3] |= (u8)(mask >> 3 * 8);
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block->hdr.bitmap[4] |= (u8)(mask >> 4 * 8);
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block->hdr.bitmap[5] |= (u8)(mask >> 5 * 8);
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block->hdr.bitmap[6] |= (u8)(mask >> 6 * 8);
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block->hdr.bitmap[7] |= (u8)(mask >> 7 * 8);
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}
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/*
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* Clear a number of contiguous bits in the directory block bitmap.
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*/
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static void afs_clear_contig_bits(union afs_xdr_dir_block *block,
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int bit, unsigned int nr_slots)
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{
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u64 mask;
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mask = (1 << nr_slots) - 1;
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mask <<= bit;
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block->hdr.bitmap[0] &= ~(u8)(mask >> 0 * 8);
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block->hdr.bitmap[1] &= ~(u8)(mask >> 1 * 8);
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block->hdr.bitmap[2] &= ~(u8)(mask >> 2 * 8);
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block->hdr.bitmap[3] &= ~(u8)(mask >> 3 * 8);
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block->hdr.bitmap[4] &= ~(u8)(mask >> 4 * 8);
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block->hdr.bitmap[5] &= ~(u8)(mask >> 5 * 8);
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block->hdr.bitmap[6] &= ~(u8)(mask >> 6 * 8);
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block->hdr.bitmap[7] &= ~(u8)(mask >> 7 * 8);
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}
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/*
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* Scan a directory block looking for a dirent of the right name.
|
*/
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static int afs_dir_scan_block(union afs_xdr_dir_block *block, struct qstr *name,
|
unsigned int blocknum)
|
{
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union afs_xdr_dirent *de;
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u64 bitmap;
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int d, len, n;
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_enter("");
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bitmap = (u64)block->hdr.bitmap[0] << 0 * 8;
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bitmap |= (u64)block->hdr.bitmap[1] << 1 * 8;
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bitmap |= (u64)block->hdr.bitmap[2] << 2 * 8;
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bitmap |= (u64)block->hdr.bitmap[3] << 3 * 8;
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bitmap |= (u64)block->hdr.bitmap[4] << 4 * 8;
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bitmap |= (u64)block->hdr.bitmap[5] << 5 * 8;
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bitmap |= (u64)block->hdr.bitmap[6] << 6 * 8;
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bitmap |= (u64)block->hdr.bitmap[7] << 7 * 8;
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for (d = (blocknum == 0 ? AFS_DIR_RESV_BLOCKS0 : AFS_DIR_RESV_BLOCKS);
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d < AFS_DIR_SLOTS_PER_BLOCK;
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d++) {
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if (!((bitmap >> d) & 1))
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continue;
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de = &block->dirents[d];
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if (de->u.valid != 1)
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continue;
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/* The block was NUL-terminated by afs_dir_check_page(). */
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len = strlen(de->u.name);
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if (len == name->len &&
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memcmp(de->u.name, name->name, name->len) == 0)
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return d;
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n = round_up(12 + len + 1 + 4, AFS_DIR_DIRENT_SIZE);
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n /= AFS_DIR_DIRENT_SIZE;
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d += n - 1;
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}
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|
return -1;
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}
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/*
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* Initialise a new directory block. Note that block 0 is special and contains
|
* some extra metadata.
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*/
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static void afs_edit_init_block(union afs_xdr_dir_block *meta,
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union afs_xdr_dir_block *block, int block_num)
|
{
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memset(block, 0, sizeof(*block));
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block->hdr.npages = htons(1);
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block->hdr.magic = AFS_DIR_MAGIC;
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block->hdr.bitmap[0] = 1;
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if (block_num == 0) {
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block->hdr.bitmap[0] = 0xff;
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block->hdr.bitmap[1] = 0x1f;
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memset(block->meta.alloc_ctrs,
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AFS_DIR_SLOTS_PER_BLOCK,
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sizeof(block->meta.alloc_ctrs));
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meta->meta.alloc_ctrs[0] =
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AFS_DIR_SLOTS_PER_BLOCK - AFS_DIR_RESV_BLOCKS0;
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}
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if (block_num < AFS_DIR_BLOCKS_WITH_CTR)
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meta->meta.alloc_ctrs[block_num] =
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AFS_DIR_SLOTS_PER_BLOCK - AFS_DIR_RESV_BLOCKS;
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}
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/*
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* Edit a directory's file data to add a new directory entry. Doing this after
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* create, mkdir, symlink, link or rename if the data version number is
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* incremented by exactly one avoids the need to re-download the entire
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* directory contents.
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*
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* The caller must hold the inode locked.
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*/
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void afs_edit_dir_add(struct afs_vnode *vnode,
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struct qstr *name, struct afs_fid *new_fid,
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enum afs_edit_dir_reason why)
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{
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union afs_xdr_dir_block *meta, *block;
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struct afs_xdr_dir_page *meta_page, *dir_page;
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union afs_xdr_dirent *de;
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struct page *page0, *page;
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unsigned int need_slots, nr_blocks, b;
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pgoff_t index;
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loff_t i_size;
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gfp_t gfp;
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int slot;
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_enter(",,{%d,%s},", name->len, name->name);
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i_size = i_size_read(&vnode->vfs_inode);
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if (i_size > AFS_DIR_BLOCK_SIZE * AFS_DIR_MAX_BLOCKS ||
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(i_size & (AFS_DIR_BLOCK_SIZE - 1))) {
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clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
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return;
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}
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gfp = vnode->vfs_inode.i_mapping->gfp_mask;
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page0 = find_or_create_page(vnode->vfs_inode.i_mapping, 0, gfp);
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if (!page0) {
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clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
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_leave(" [fgp]");
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return;
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}
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/* Work out how many slots we're going to need. */
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need_slots = round_up(12 + name->len + 1 + 4, AFS_DIR_DIRENT_SIZE);
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need_slots /= AFS_DIR_DIRENT_SIZE;
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meta_page = kmap(page0);
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meta = &meta_page->blocks[0];
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if (i_size == 0)
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goto new_directory;
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nr_blocks = i_size / AFS_DIR_BLOCK_SIZE;
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/* Find a block that has sufficient slots available. Each VM page
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* contains two or more directory blocks.
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*/
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for (b = 0; b < nr_blocks + 1; b++) {
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/* If the directory extended into a new page, then we need to
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* tack a new page on the end.
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*/
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index = b / AFS_DIR_BLOCKS_PER_PAGE;
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if (index == 0) {
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page = page0;
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dir_page = meta_page;
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} else {
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if (nr_blocks >= AFS_DIR_MAX_BLOCKS)
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goto error;
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gfp = vnode->vfs_inode.i_mapping->gfp_mask;
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page = find_or_create_page(vnode->vfs_inode.i_mapping,
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index, gfp);
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if (!page)
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goto error;
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if (!PagePrivate(page))
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attach_page_private(page, (void *)1);
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dir_page = kmap(page);
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}
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/* Abandon the edit if we got a callback break. */
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if (!test_bit(AFS_VNODE_DIR_VALID, &vnode->flags))
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goto invalidated;
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block = &dir_page->blocks[b % AFS_DIR_BLOCKS_PER_PAGE];
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_debug("block %u: %2u %3u %u",
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b,
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(b < AFS_DIR_BLOCKS_WITH_CTR) ? meta->meta.alloc_ctrs[b] : 99,
|
ntohs(block->hdr.npages),
|
ntohs(block->hdr.magic));
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|
/* Initialise the block if necessary. */
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if (b == nr_blocks) {
|
_debug("init %u", b);
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afs_edit_init_block(meta, block, b);
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afs_set_i_size(vnode, (b + 1) * AFS_DIR_BLOCK_SIZE);
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}
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/* Only lower dir pages have a counter in the header. */
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if (b >= AFS_DIR_BLOCKS_WITH_CTR ||
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meta->meta.alloc_ctrs[b] >= need_slots) {
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/* We need to try and find one or more consecutive
|
* slots to hold the entry.
|
*/
|
slot = afs_find_contig_bits(block, need_slots);
|
if (slot >= 0) {
|
_debug("slot %u", slot);
|
goto found_space;
|
}
|
}
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|
if (page != page0) {
|
unlock_page(page);
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kunmap(page);
|
put_page(page);
|
}
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}
|
|
/* There are no spare slots of sufficient size, yet the operation
|
* succeeded. Download the directory again.
|
*/
|
trace_afs_edit_dir(vnode, why, afs_edit_dir_create_nospc, 0, 0, 0, 0, name->name);
|
clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
|
goto out_unmap;
|
|
new_directory:
|
afs_edit_init_block(meta, meta, 0);
|
i_size = AFS_DIR_BLOCK_SIZE;
|
afs_set_i_size(vnode, i_size);
|
slot = AFS_DIR_RESV_BLOCKS0;
|
page = page0;
|
block = meta;
|
nr_blocks = 1;
|
b = 0;
|
|
found_space:
|
/* Set the dirent slot. */
|
trace_afs_edit_dir(vnode, why, afs_edit_dir_create, b, slot,
|
new_fid->vnode, new_fid->unique, name->name);
|
de = &block->dirents[slot];
|
de->u.valid = 1;
|
de->u.unused[0] = 0;
|
de->u.hash_next = 0; // TODO: Really need to maintain this
|
de->u.vnode = htonl(new_fid->vnode);
|
de->u.unique = htonl(new_fid->unique);
|
memcpy(de->u.name, name->name, name->len + 1);
|
de->u.name[name->len] = 0;
|
|
/* Adjust the bitmap. */
|
afs_set_contig_bits(block, slot, need_slots);
|
if (page != page0) {
|
unlock_page(page);
|
kunmap(page);
|
put_page(page);
|
}
|
|
/* Adjust the allocation counter. */
|
if (b < AFS_DIR_BLOCKS_WITH_CTR)
|
meta->meta.alloc_ctrs[b] -= need_slots;
|
|
inode_inc_iversion_raw(&vnode->vfs_inode);
|
afs_stat_v(vnode, n_dir_cr);
|
_debug("Insert %s in %u[%u]", name->name, b, slot);
|
|
out_unmap:
|
unlock_page(page0);
|
kunmap(page0);
|
put_page(page0);
|
_leave("");
|
return;
|
|
invalidated:
|
trace_afs_edit_dir(vnode, why, afs_edit_dir_create_inval, 0, 0, 0, 0, name->name);
|
clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
|
if (page != page0) {
|
kunmap(page);
|
put_page(page);
|
}
|
goto out_unmap;
|
|
error:
|
trace_afs_edit_dir(vnode, why, afs_edit_dir_create_error, 0, 0, 0, 0, name->name);
|
clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
|
goto out_unmap;
|
}
|
|
/*
|
* Edit a directory's file data to remove a new directory entry. Doing this
|
* after unlink, rmdir or rename if the data version number is incremented by
|
* exactly one avoids the need to re-download the entire directory contents.
|
*
|
* The caller must hold the inode locked.
|
*/
|
void afs_edit_dir_remove(struct afs_vnode *vnode,
|
struct qstr *name, enum afs_edit_dir_reason why)
|
{
|
struct afs_xdr_dir_page *meta_page, *dir_page;
|
union afs_xdr_dir_block *meta, *block;
|
union afs_xdr_dirent *de;
|
struct page *page0, *page;
|
unsigned int need_slots, nr_blocks, b;
|
pgoff_t index;
|
loff_t i_size;
|
int slot;
|
|
_enter(",,{%d,%s},", name->len, name->name);
|
|
i_size = i_size_read(&vnode->vfs_inode);
|
if (i_size < AFS_DIR_BLOCK_SIZE ||
|
i_size > AFS_DIR_BLOCK_SIZE * AFS_DIR_MAX_BLOCKS ||
|
(i_size & (AFS_DIR_BLOCK_SIZE - 1))) {
|
clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
|
return;
|
}
|
nr_blocks = i_size / AFS_DIR_BLOCK_SIZE;
|
|
page0 = find_lock_page(vnode->vfs_inode.i_mapping, 0);
|
if (!page0) {
|
clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
|
_leave(" [fgp]");
|
return;
|
}
|
|
/* Work out how many slots we're going to discard. */
|
need_slots = round_up(12 + name->len + 1 + 4, AFS_DIR_DIRENT_SIZE);
|
need_slots /= AFS_DIR_DIRENT_SIZE;
|
|
meta_page = kmap(page0);
|
meta = &meta_page->blocks[0];
|
|
/* Find a page that has sufficient slots available. Each VM page
|
* contains two or more directory blocks.
|
*/
|
for (b = 0; b < nr_blocks; b++) {
|
index = b / AFS_DIR_BLOCKS_PER_PAGE;
|
if (index != 0) {
|
page = find_lock_page(vnode->vfs_inode.i_mapping, index);
|
if (!page)
|
goto error;
|
dir_page = kmap(page);
|
} else {
|
page = page0;
|
dir_page = meta_page;
|
}
|
|
/* Abandon the edit if we got a callback break. */
|
if (!test_bit(AFS_VNODE_DIR_VALID, &vnode->flags))
|
goto invalidated;
|
|
block = &dir_page->blocks[b % AFS_DIR_BLOCKS_PER_PAGE];
|
|
if (b > AFS_DIR_BLOCKS_WITH_CTR ||
|
meta->meta.alloc_ctrs[b] <= AFS_DIR_SLOTS_PER_BLOCK - 1 - need_slots) {
|
slot = afs_dir_scan_block(block, name, b);
|
if (slot >= 0)
|
goto found_dirent;
|
}
|
|
if (page != page0) {
|
unlock_page(page);
|
kunmap(page);
|
put_page(page);
|
}
|
}
|
|
/* Didn't find the dirent to clobber. Download the directory again. */
|
trace_afs_edit_dir(vnode, why, afs_edit_dir_delete_noent,
|
0, 0, 0, 0, name->name);
|
clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
|
goto out_unmap;
|
|
found_dirent:
|
de = &block->dirents[slot];
|
|
trace_afs_edit_dir(vnode, why, afs_edit_dir_delete, b, slot,
|
ntohl(de->u.vnode), ntohl(de->u.unique),
|
name->name);
|
|
memset(de, 0, sizeof(*de) * need_slots);
|
|
/* Adjust the bitmap. */
|
afs_clear_contig_bits(block, slot, need_slots);
|
if (page != page0) {
|
unlock_page(page);
|
kunmap(page);
|
put_page(page);
|
}
|
|
/* Adjust the allocation counter. */
|
if (b < AFS_DIR_BLOCKS_WITH_CTR)
|
meta->meta.alloc_ctrs[b] += need_slots;
|
|
inode_set_iversion_raw(&vnode->vfs_inode, vnode->status.data_version);
|
afs_stat_v(vnode, n_dir_rm);
|
_debug("Remove %s from %u[%u]", name->name, b, slot);
|
|
out_unmap:
|
unlock_page(page0);
|
kunmap(page0);
|
put_page(page0);
|
_leave("");
|
return;
|
|
invalidated:
|
trace_afs_edit_dir(vnode, why, afs_edit_dir_delete_inval,
|
0, 0, 0, 0, name->name);
|
clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
|
if (page != page0) {
|
unlock_page(page);
|
kunmap(page);
|
put_page(page);
|
}
|
goto out_unmap;
|
|
error:
|
trace_afs_edit_dir(vnode, why, afs_edit_dir_delete_error,
|
0, 0, 0, 0, name->name);
|
clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
|
goto out_unmap;
|
}
|
