From 63a4681ff39cb63314b8ff41319e70fb0e606ed2 Mon Sep 17 00:00:00 2001 From: David Howells Date: Fri, 6 Apr 2018 14:17:25 +0100 Subject: afs: Locally edit directory data for mkdir/create/unlink/... Locally edit the contents of an AFS directory upon a successful inode operation that modifies that directory (such as mkdir, create and unlink) so that we can avoid the current practice of re-downloading the directory after each change. This is viable provided that the directory version number we get back from the modifying RPC op is exactly incremented by 1 from what we had previously. The data in the directory contents is in a defined format that we have to parse locally to perform lookups and readdir, so modifying isn't a problem. If the edit fails, we just clear the VALID flag on the directory and it will be reloaded next time it is needed. Signed-off-by: David Howells --- fs/afs/dir_edit.c | 505 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 505 insertions(+) create mode 100644 fs/afs/dir_edit.c (limited to 'fs/afs/dir_edit.c') diff --git a/fs/afs/dir_edit.c b/fs/afs/dir_edit.c new file mode 100644 index 000000000000..8b400f5aead5 --- /dev/null +++ b/fs/afs/dir_edit.c @@ -0,0 +1,505 @@ +/* AFS filesystem directory editing + * + * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * 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. + */ + +#include +#include +#include +#include +#include +#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; +} -- cgit v1.2.3