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linux/fs/afs/dir_edit.c
David Howells 247d65fb12
afs: Fix missing subdir edit when renamed between parent dirs 
When rename moves an AFS subdirectory between parent directories, the
subdir also needs a bit of editing: the ".." entry needs updating to point
to the new parent (though I don't make use of the info) and the DV needs
incrementing by 1 to reflect the change of content.  The server also sends
a callback break notification on the subdirectory if we have one, but we
can take care of recovering the promise next time we access the subdir.

This can be triggered by something like:

    mount -t afs %example.com:xfstest.test20 /xfstest.test/
    mkdir /xfstest.test/{aaa,bbb,aaa/ccc}
    touch /xfstest.test/bbb/ccc/d
    mv /xfstest.test/{aaa/ccc,bbb/ccc}
    touch /xfstest.test/bbb/ccc/e

When the pathwalk for the second touch hits "ccc", kafs spots that the DV
is incorrect and downloads it again (so the fix is not critical).

Fix this, if the rename target is a directory and the old and new
parents are different, by:

 (1) Incrementing the DV number of the target locally.

 (2) Editing the ".." entry in the target to refer to its new parent's
     vnode ID and uniquifier.

Link: https://lore.kernel.org/r/3340431.1729680010@warthog.procyon.org.uk
Fixes: 63a4681ff3 ("afs: Locally edit directory data for mkdir/create/unlink/...")
cc: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-10-24 13:50:27 +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;
mask = (1 << nr_slots) - 1;
mask <<= bit;
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);
}
/*
* 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;
mask = (1 << nr_slots) - 1;
mask <<= bit;
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);
}
/*
* Get a new directory folio.
*/
static struct folio *afs_dir_get_folio(struct afs_vnode *vnode, pgoff_t index)
{
struct address_space *mapping = vnode->netfs.inode.i_mapping;
struct folio *folio;
folio = __filemap_get_folio(mapping, index,
FGP_LOCK | FGP_ACCESSED | FGP_CREAT,
mapping->gfp_mask);
if (IS_ERR(folio)) {
clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
return NULL;
}
if (!folio_test_private(folio))
folio_attach_private(folio, (void *)1);
return folio;
}
/*
* Scan a directory block looking for a dirent of the right name.
*/
static int afs_dir_scan_block(const union afs_xdr_dir_block *block, const struct qstr *name,
unsigned int blocknum)
{
const 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;
union afs_xdr_dirent *de;
struct folio *folio0, *folio;
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->netfs.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;
}
folio0 = afs_dir_get_folio(vnode, 0);
if (!folio0) {
_leave(" [fgp]");
return;
}
/* Work out how many slots we're going to need. */
need_slots = afs_dir_calc_slots(name->len);
meta = kmap_local_folio(folio0, 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 folio
* contains two or more directory blocks.
*/
for (b = 0; b < nr_blocks + 1; b++) {
/* If the directory extended into a new folio, then we need to
* tack a new folio on the end.
*/
index = b / AFS_DIR_BLOCKS_PER_PAGE;
if (nr_blocks >= AFS_DIR_MAX_BLOCKS)
goto error;
if (index >= folio_nr_pages(folio0)) {
folio = afs_dir_get_folio(vnode, index);
if (!folio)
goto error;
} else {
folio = folio0;
}
block = kmap_local_folio(folio, b * AFS_DIR_BLOCK_SIZE - folio_pos(folio));
/* Abandon the edit if we got a callback break. */
if (!test_bit(AFS_VNODE_DIR_VALID, &vnode->flags))
goto invalidated;
_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);
afs_set_i_size(vnode, (b + 1) * AFS_DIR_BLOCK_SIZE);
}
/* Only lower dir blocks 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;
}
}
kunmap_local(block);
if (folio != folio0) {
folio_unlock(folio);
folio_put(folio);
}
}
/* 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;
folio = folio0;
block = kmap_local_folio(folio, 0);
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);
kunmap_local(block);
if (folio != folio0) {
folio_unlock(folio);
folio_put(folio);
}
/* Adjust the allocation counter. */
if (b < AFS_DIR_BLOCKS_WITH_CTR)
meta->meta.alloc_ctrs[b] -= need_slots;
inode_inc_iversion_raw(&vnode->netfs.inode);
afs_stat_v(vnode, n_dir_cr);
_debug("Insert %s in %u[%u]", name->name, b, slot);
out_unmap:
kunmap_local(meta);
folio_unlock(folio0);
folio_put(folio0);
_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);
kunmap_local(block);
if (folio != folio0) {
folio_unlock(folio);
folio_put(folio);
}
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)
{
union afs_xdr_dir_block *meta, *block;
union afs_xdr_dirent *de;
struct folio *folio0, *folio;
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->netfs.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;
folio0 = afs_dir_get_folio(vnode, 0);
if (!folio0) {
_leave(" [fgp]");
return;
}
/* Work out how many slots we're going to discard. */
need_slots = afs_dir_calc_slots(name->len);
meta = kmap_local_folio(folio0, 0);
/* Find a block that has sufficient slots available. Each folio
* contains two or more directory blocks.
*/
for (b = 0; b < nr_blocks; b++) {
index = b / AFS_DIR_BLOCKS_PER_PAGE;
if (index >= folio_nr_pages(folio0)) {
folio = afs_dir_get_folio(vnode, index);
if (!folio)
goto error;
} else {
folio = folio0;
}
block = kmap_local_folio(folio, b * AFS_DIR_BLOCK_SIZE - folio_pos(folio));
/* Abandon the edit if we got a callback break. */
if (!test_bit(AFS_VNODE_DIR_VALID, &vnode->flags))
goto invalidated;
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;
}
kunmap_local(block);
if (folio != folio0) {
folio_unlock(folio);
folio_put(folio);
}
}
/* 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);
kunmap_local(block);
if (folio != folio0) {
folio_unlock(folio);
folio_put(folio);
}
/* Adjust the allocation counter. */
if (b < AFS_DIR_BLOCKS_WITH_CTR)
meta->meta.alloc_ctrs[b] += need_slots;
inode_set_iversion_raw(&vnode->netfs.inode, vnode->status.data_version);
afs_stat_v(vnode, n_dir_rm);
_debug("Remove %s from %u[%u]", name->name, b, slot);
out_unmap:
kunmap_local(meta);
folio_unlock(folio0);
folio_put(folio0);
_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);
kunmap_local(block);
if (folio != folio0) {
folio_unlock(folio);
folio_put(folio);
}
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;
}
/*
* Edit a subdirectory that has been moved between directories to update the
* ".." entry.
*/
void afs_edit_dir_update_dotdot(struct afs_vnode *vnode, struct afs_vnode *new_dvnode,
enum afs_edit_dir_reason why)
{
union afs_xdr_dir_block *block;
union afs_xdr_dirent *de;
struct folio *folio;
unsigned int nr_blocks, b;
pgoff_t index;
loff_t i_size;
int slot;
_enter("");
i_size = i_size_read(&vnode->netfs.inode);
if (i_size < AFS_DIR_BLOCK_SIZE) {
clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
return;
}
nr_blocks = i_size / AFS_DIR_BLOCK_SIZE;
/* Find a block that has sufficient slots available. Each folio
* contains two or more directory blocks.
*/
for (b = 0; b < nr_blocks; b++) {
index = b / AFS_DIR_BLOCKS_PER_PAGE;
folio = afs_dir_get_folio(vnode, index);
if (!folio)
goto error;
block = kmap_local_folio(folio, b * AFS_DIR_BLOCK_SIZE - folio_pos(folio));
/* Abandon the edit if we got a callback break. */
if (!test_bit(AFS_VNODE_DIR_VALID, &vnode->flags))
goto invalidated;
slot = afs_dir_scan_block(block, &dotdot_name, b);
if (slot >= 0)
goto found_dirent;
kunmap_local(block);
folio_unlock(folio);
folio_put(folio);
}
/* Didn't find the dirent to clobber. Download the directory again. */
trace_afs_edit_dir(vnode, why, afs_edit_dir_update_nodd,
0, 0, 0, 0, "..");
clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
goto out;
found_dirent:
de = &block->dirents[slot];
de->u.vnode = htonl(new_dvnode->fid.vnode);
de->u.unique = htonl(new_dvnode->fid.unique);
trace_afs_edit_dir(vnode, why, afs_edit_dir_update_dd, b, slot,
ntohl(de->u.vnode), ntohl(de->u.unique), "..");
kunmap_local(block);
folio_unlock(folio);
folio_put(folio);
inode_set_iversion_raw(&vnode->netfs.inode, vnode->status.data_version);
out:
_leave("");
return;
invalidated:
kunmap_local(block);
folio_unlock(folio);
folio_put(folio);
trace_afs_edit_dir(vnode, why, afs_edit_dir_update_inval,
0, 0, 0, 0, "..");
clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
goto out;
error:
trace_afs_edit_dir(vnode, why, afs_edit_dir_update_error,
0, 0, 0, 0, "..");
clear_bit(AFS_VNODE_DIR_VALID, &vnode->flags);
goto out;
}
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