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alistair23-linux/fs/afs/dir_edit.c
Thomas Gleixner b4d0d230cc treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 36 
Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public licence as published by
  the free software foundation either version 2 of the licence or at
  your option any later version

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 114 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190520170857.552531963@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-24 17:27:11 +02:00

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// SPDX-License-Identifier: GPL-2.0-or-later
/* AFS filesystem directory editing
*
* Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/pagemap.h>
#include <linux/iversion.h>
#include "internal.h"
#include "xdr_fs.h"
/*
* Find a number of contiguous clear bits in a directory block bitmask.
*
* 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
* slot. nr_slots is between 1 and 9.
*/
static int afs_find_contig_bits(union afs_xdr_dir_block *block, unsigned int nr_slots)
{
u64 bitmap;
u32 mask;
int bit, n;
bitmap = (u64)block->hdr.bitmap[0] << 0 * 8;
bitmap |= (u64)block->hdr.bitmap[1] << 1 * 8;
bitmap |= (u64)block->hdr.bitmap[2] << 2 * 8;
bitmap |= (u64)block->hdr.bitmap[3] << 3 * 8;
bitmap |= (u64)block->hdr.bitmap[4] << 4 * 8;
bitmap |= (u64)block->hdr.bitmap[5] << 5 * 8;
bitmap |= (u64)block->hdr.bitmap[6] << 6 * 8;
bitmap |= (u64)block->hdr.bitmap[7] << 7 * 8;
bitmap >>= 1; /* The first entry is metadata */
bit = 1;
mask = (1 << nr_slots) - 1;
do {
if (sizeof(unsigned long) == 8)
n = ffz(bitmap);
else
n = ((u32)bitmap) != 0 ?
ffz((u32)bitmap) :
ffz((u32)(bitmap >> 32)) + 32;
bitmap >>= n;
bit += n;
if ((bitmap & mask) == 0) {
if (bit > 64 - nr_slots)
return -1;
return bit;
}
n = __ffs(bitmap);
bitmap >>= n;
bit += n;
} while (bitmap);
return -1;
}
/*
* Set a number of contiguous bits in the directory block bitmap.
*/
static void afs_set_contig_bits(union afs_xdr_dir_block *block,
int bit, unsigned int nr_slots)
{
u64 mask, before, after;
mask = (1 << nr_slots) - 1;
mask <<= bit;
before = *(u64 *)block->hdr.bitmap;
block->hdr.bitmap[0] |= (u8)(mask >> 0 * 8);
block->hdr.bitmap[1] |= (u8)(mask >> 1 * 8);
block->hdr.bitmap[2] |= (u8)(mask >> 2 * 8);
block->hdr.bitmap[3] |= (u8)(mask >> 3 * 8);
block->hdr.bitmap[4] |= (u8)(mask >> 4 * 8);
block->hdr.bitmap[5] |= (u8)(mask >> 5 * 8);
block->hdr.bitmap[6] |= (u8)(mask >> 6 * 8);
block->hdr.bitmap[7] |= (u8)(mask >> 7 * 8);
after = *(u64 *)block->hdr.bitmap;
}
/*
* Clear a number of contiguous bits in the directory block bitmap.
*/
static void afs_clear_contig_bits(union afs_xdr_dir_block *block,
int bit, unsigned int nr_slots)
{
u64 mask, before, after;
mask = (1 << nr_slots) - 1;
mask <<= bit;
before = *(u64 *)block->hdr.bitmap;
block->hdr.bitmap[0] &= ~(u8)(mask >> 0 * 8);
block->hdr.bitmap[1] &= ~(u8)(mask >> 1 * 8);
block->hdr.bitmap[2] &= ~(u8)(mask >> 2 * 8);
block->hdr.bitmap[3] &= ~(u8)(mask >> 3 * 8);
block->hdr.bitmap[4] &= ~(u8)(mask >> 4 * 8);
block->hdr.bitmap[5] &= ~(u8)(mask >> 5 * 8);
block->hdr.bitmap[6] &= ~(u8)(mask >> 6 * 8);
block->hdr.bitmap[7] &= ~(u8)(mask >> 7 * 8);
after = *(u64 *)block->hdr.bitmap;
}
/*
* Scan a directory block looking for a dirent of the right name.
*/
static int afs_dir_scan_block(union afs_xdr_dir_block *block, struct qstr *name,
unsigned int blocknum)
{
union afs_xdr_dirent *de;
u64 bitmap;
int d, len, n;
_enter("");
bitmap = (u64)block->hdr.bitmap[0] << 0 * 8;
bitmap |= (u64)block->hdr.bitmap[1] << 1 * 8;
bitmap |= (u64)block->hdr.bitmap[2] << 2 * 8;
bitmap |= (u64)block->hdr.bitmap[3] << 3 * 8;
bitmap |= (u64)block->hdr.bitmap[4] << 4 * 8;
bitmap |= (u64)block->hdr.bitmap[5] << 5 * 8;
bitmap |= (u64)block->hdr.bitmap[6] << 6 * 8;
bitmap |= (u64)block->hdr.bitmap[7] << 7 * 8;
for (d = (blocknum == 0 ? AFS_DIR_RESV_BLOCKS0 : AFS_DIR_RESV_BLOCKS);
d < AFS_DIR_SLOTS_PER_BLOCK;
d++) {
if (!((bitmap >> d) & 1))
continue;
de = &block->dirents[d];
if (de->u.valid != 1)
continue;
/* The block was NUL-terminated by afs_dir_check_page(). */
len = strlen(de->u.name);
if (len == name->len &&
memcmp(de->u.name, name->name, name->len) == 0)
return d;
n = round_up(12 + len + 1 + 4, AFS_DIR_DIRENT_SIZE);
n /= AFS_DIR_DIRENT_SIZE;
d += n - 1;
}
return -1;
}
/*
* Initialise a new directory block. Note that block 0 is special and contains
* some extra metadata.
*/
static void afs_edit_init_block(union afs_xdr_dir_block *meta,
union afs_xdr_dir_block *block, int block_num)
{
memset(block, 0, sizeof(*block));
block->hdr.npages = htons(1);
block->hdr.magic = AFS_DIR_MAGIC;
block->hdr.bitmap[0] = 1;
if (block_num == 0) {
block->hdr.bitmap[0] = 0xff;
block->hdr.bitmap[1] = 0x1f;
memset(block->meta.alloc_ctrs,
AFS_DIR_SLOTS_PER_BLOCK,
sizeof(block->meta.alloc_ctrs));
meta->meta.alloc_ctrs[0] =
AFS_DIR_SLOTS_PER_BLOCK - AFS_DIR_RESV_BLOCKS0;
}
if (block_num < AFS_DIR_BLOCKS_WITH_CTR)
meta->meta.alloc_ctrs[block_num] =
AFS_DIR_SLOTS_PER_BLOCK - AFS_DIR_RESV_BLOCKS;
}
/*
* Edit a directory's file data to add a new directory entry. Doing this after
* create, mkdir, symlink, link 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_add(struct afs_vnode *vnode,
struct qstr *name, struct afs_fid *new_fid,
enum afs_edit_dir_reason why)
{
union afs_xdr_dir_block *meta, *block;
struct afs_xdr_dir_page *meta_page, *dir_page;
union afs_xdr_dirent *de;
struct page *page0, *page;
unsigned int need_slots, nr_blocks, b;
pgoff_t index;
loff_t i_size;
gfp_t gfp;
int slot;
_enter(",,{%d,%s},", name->len, name->name);
i_size = i_size_read(&vnode->vfs_inode);
if (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;
}
gfp = vnode->vfs_inode.i_mapping->gfp_mask;
page0 = find_or_create_page(vnode->vfs_inode.i_mapping, 0, gfp);
if (!page0) {
clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
_leave(" [fgp]");
return;
}
/* Work out how many slots we're going to need. */
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];
if (i_size == 0)
goto new_directory;
nr_blocks = i_size / AFS_DIR_BLOCK_SIZE;
/* Find a block that has sufficient slots available. Each VM page
* contains two or more directory blocks.
*/
for (b = 0; b < nr_blocks + 1; b++) {
/* If the directory extended into a new page, then we need to
* tack a new page on the end.
*/
index = b / AFS_DIR_BLOCKS_PER_PAGE;
if (index == 0) {
page = page0;
dir_page = meta_page;
} else {
if (nr_blocks >= AFS_DIR_MAX_BLOCKS)
goto error;
gfp = vnode->vfs_inode.i_mapping->gfp_mask;
page = find_or_create_page(vnode->vfs_inode.i_mapping,
index, gfp);
if (!page)
goto error;
if (!PagePrivate(page)) {
set_page_private(page, 1);
SetPagePrivate(page);
}
dir_page = kmap(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];
_debug("block %u: %2u %3u %u",
b,
(b < AFS_DIR_BLOCKS_WITH_CTR) ? meta->meta.alloc_ctrs[b] : 99,
ntohs(block->hdr.npages),
ntohs(block->hdr.magic));
/* Initialise the block if necessary. */
if (b == nr_blocks) {
_debug("init %u", b);
afs_edit_init_block(meta, block, b);
i_size_write(&vnode->vfs_inode, (b + 1) * AFS_DIR_BLOCK_SIZE);
}
/* Only lower dir pages have a counter in the header. */
if (b >= AFS_DIR_BLOCKS_WITH_CTR ||
meta->meta.alloc_ctrs[b] >= need_slots) {
/* 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;
}
}
if (page != page0) {
unlock_page(page);
kunmap(page);
put_page(page);
}
}
/* 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;
i_size_write(&vnode->vfs_inode, 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;
}
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