Linux 6.13-rc4

[linux.git] / fs / btrfs / lzo.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2008 Oracle.  All rights reserved.
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/sched.h>
#include <linux/pagemap.h>
#include <linux/bio.h>
#include <linux/lzo.h>
#include <linux/refcount.h>
#include "messages.h"
#include "compression.h"
#include "ctree.h"
#include "super.h"
#include "btrfs_inode.h"

#define LZO_LEN 4

/*
 * Btrfs LZO compression format
 *
 * Regular and inlined LZO compressed data extents consist of:
 *
 * 1.  Header
 *     Fixed size. LZO_LEN (4) bytes long, LE32.
 *     Records the total size (including the header) of compressed data.
 *
 * 2.  Segment(s)
 *     Variable size. Each segment includes one segment header, followed by data
 *     payload.
 *     One regular LZO compressed extent can have one or more segments.
 *     For inlined LZO compressed extent, only one segment is allowed.
 *     One segment represents at most one sector of uncompressed data.
 *
 * 2.1 Segment header
 *     Fixed size. LZO_LEN (4) bytes long, LE32.
 *     Records the total size of the segment (not including the header).
 *     Segment header never crosses sector boundary, thus it's possible to
 *     have at most 3 padding zeros at the end of the sector.
 *
 * 2.2 Data Payload
 *     Variable size. Size up limit should be lzo1x_worst_compress(sectorsize)
 *     which is 4419 for a 4KiB sectorsize.
 *
 * Example with 4K sectorsize:
 * Page 1:
 *          0     0x2   0x4   0x6   0x8   0xa   0xc   0xe     0x10
 * 0x0000   |  Header   | SegHdr 01 | Data payload 01 ...     |
 * ...
 * 0x0ff0   | SegHdr  N | Data payload  N     ...          |00|
 *                                                          ^^ padding zeros
 * Page 2:
 * 0x1000   | SegHdr N+1| Data payload N+1 ...                |
 */

#define WORKSPACE_BUF_LENGTH    (lzo1x_worst_compress(PAGE_SIZE))
#define WORKSPACE_CBUF_LENGTH   (lzo1x_worst_compress(PAGE_SIZE))

struct workspace {
        void *mem;
        void *buf;      /* where decompressed data goes */
        void *cbuf;     /* where compressed data goes */
        struct list_head list;
};

static struct workspace_manager wsm;

void lzo_free_workspace(struct list_head *ws)
{
        struct workspace *workspace = list_entry(ws, struct workspace, list);

        kvfree(workspace->buf);
        kvfree(workspace->cbuf);
        kvfree(workspace->mem);
        kfree(workspace);
}

struct list_head *lzo_alloc_workspace(void)
{
        struct workspace *workspace;

        workspace = kzalloc(sizeof(*workspace), GFP_KERNEL);
        if (!workspace)
                return ERR_PTR(-ENOMEM);

        workspace->mem = kvmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL | __GFP_NOWARN);
        workspace->buf = kvmalloc(WORKSPACE_BUF_LENGTH, GFP_KERNEL | __GFP_NOWARN);
        workspace->cbuf = kvmalloc(WORKSPACE_CBUF_LENGTH, GFP_KERNEL | __GFP_NOWARN);
        if (!workspace->mem || !workspace->buf || !workspace->cbuf)
                goto fail;

        INIT_LIST_HEAD(&workspace->list);

        return &workspace->list;
fail:
        lzo_free_workspace(&workspace->list);
        return ERR_PTR(-ENOMEM);
}

static inline void write_compress_length(char *buf, size_t len)
{
        __le32 dlen;

        dlen = cpu_to_le32(len);
        memcpy(buf, &dlen, LZO_LEN);
}

static inline size_t read_compress_length(const char *buf)
{
        __le32 dlen;

        memcpy(&dlen, buf, LZO_LEN);
        return le32_to_cpu(dlen);
}

/*
 * Will do:
 *
 * - Write a segment header into the destination
 * - Copy the compressed buffer into the destination
 * - Make sure we have enough space in the last sector to fit a segment header
 *   If not, we will pad at most (LZO_LEN (4)) - 1 bytes of zeros.
 *
 * Will allocate new pages when needed.
 */
static int copy_compressed_data_to_page(char *compressed_data,
                                        size_t compressed_size,
                                        struct folio **out_folios,
                                        unsigned long max_nr_folio,
                                        u32 *cur_out,
                                        const u32 sectorsize)
{
        u32 sector_bytes_left;
        u32 orig_out;
        struct folio *cur_folio;
        char *kaddr;

        if ((*cur_out / PAGE_SIZE) >= max_nr_folio)
                return -E2BIG;

        /*
         * We never allow a segment header crossing sector boundary, previous
         * run should ensure we have enough space left inside the sector.
         */
        ASSERT((*cur_out / sectorsize) == (*cur_out + LZO_LEN - 1) / sectorsize);

        cur_folio = out_folios[*cur_out / PAGE_SIZE];
        /* Allocate a new page */
        if (!cur_folio) {
                cur_folio = btrfs_alloc_compr_folio();
                if (!cur_folio)
                        return -ENOMEM;
                out_folios[*cur_out / PAGE_SIZE] = cur_folio;
        }

        kaddr = kmap_local_folio(cur_folio, 0);
        write_compress_length(kaddr + offset_in_page(*cur_out),
                              compressed_size);
        *cur_out += LZO_LEN;

        orig_out = *cur_out;

        /* Copy compressed data */
        while (*cur_out - orig_out < compressed_size) {
                u32 copy_len = min_t(u32, sectorsize - *cur_out % sectorsize,
                                     orig_out + compressed_size - *cur_out);

                kunmap_local(kaddr);

                if ((*cur_out / PAGE_SIZE) >= max_nr_folio)
                        return -E2BIG;

                cur_folio = out_folios[*cur_out / PAGE_SIZE];
                /* Allocate a new page */
                if (!cur_folio) {
                        cur_folio = btrfs_alloc_compr_folio();
                        if (!cur_folio)
                                return -ENOMEM;
                        out_folios[*cur_out / PAGE_SIZE] = cur_folio;
                }
                kaddr = kmap_local_folio(cur_folio, 0);

                memcpy(kaddr + offset_in_page(*cur_out),
                       compressed_data + *cur_out - orig_out, copy_len);

                *cur_out += copy_len;
        }

        /*
         * Check if we can fit the next segment header into the remaining space
         * of the sector.
         */
        sector_bytes_left = round_up(*cur_out, sectorsize) - *cur_out;
        if (sector_bytes_left >= LZO_LEN || sector_bytes_left == 0)
                goto out;

        /* The remaining size is not enough, pad it with zeros */
        memset(kaddr + offset_in_page(*cur_out), 0,
               sector_bytes_left);
        *cur_out += sector_bytes_left;

out:
        kunmap_local(kaddr);
        return 0;
}

int lzo_compress_folios(struct list_head *ws, struct address_space *mapping,
                        u64 start, struct folio **folios, unsigned long *out_folios,
                        unsigned long *total_in, unsigned long *total_out)
{
        struct workspace *workspace = list_entry(ws, struct workspace, list);
        const u32 sectorsize = inode_to_fs_info(mapping->host)->sectorsize;
        struct folio *folio_in = NULL;
        char *sizes_ptr;
        const unsigned long max_nr_folio = *out_folios;
        int ret = 0;
        /* Points to the file offset of input data */
        u64 cur_in = start;
        /* Points to the current output byte */
        u32 cur_out = 0;
        u32 len = *total_out;

        ASSERT(max_nr_folio > 0);
        *out_folios = 0;
        *total_out = 0;
        *total_in = 0;

        /*
         * Skip the header for now, we will later come back and write the total
         * compressed size
         */
        cur_out += LZO_LEN;
        while (cur_in < start + len) {
                char *data_in;
                const u32 sectorsize_mask = sectorsize - 1;
                u32 sector_off = (cur_in - start) & sectorsize_mask;
                u32 in_len;
                size_t out_len;

                /* Get the input page first */
                if (!folio_in) {
                        ret = btrfs_compress_filemap_get_folio(mapping, cur_in, &folio_in);
                        if (ret < 0)
                                goto out;
                }

                /* Compress at most one sector of data each time */
                in_len = min_t(u32, start + len - cur_in, sectorsize - sector_off);
                ASSERT(in_len);
                data_in = kmap_local_folio(folio_in, 0);
                ret = lzo1x_1_compress(data_in +
                                       offset_in_page(cur_in), in_len,
                                       workspace->cbuf, &out_len,
                                       workspace->mem);
                kunmap_local(data_in);
                if (unlikely(ret < 0)) {
                        /* lzo1x_1_compress never fails. */
                        ret = -EIO;
                        goto out;
                }

                ret = copy_compressed_data_to_page(workspace->cbuf, out_len,
                                                   folios, max_nr_folio,
                                                   &cur_out, sectorsize);
                if (ret < 0)
                        goto out;

                cur_in += in_len;

                /*
                 * Check if we're making it bigger after two sectors.  And if
                 * it is so, give up.
                 */
                if (cur_in - start > sectorsize * 2 && cur_in - start < cur_out) {
                        ret = -E2BIG;
                        goto out;
                }

                /* Check if we have reached page boundary */
                if (PAGE_ALIGNED(cur_in)) {
                        folio_put(folio_in);
                        folio_in = NULL;
                }
        }

        /* Store the size of all chunks of compressed data */
        sizes_ptr = kmap_local_folio(folios[0], 0);
        write_compress_length(sizes_ptr, cur_out);
        kunmap_local(sizes_ptr);

        ret = 0;
        *total_out = cur_out;
        *total_in = cur_in - start;
out:
        if (folio_in)
                folio_put(folio_in);
        *out_folios = DIV_ROUND_UP(cur_out, PAGE_SIZE);
        return ret;
}

/*
 * Copy the compressed segment payload into @dest.
 *
 * For the payload there will be no padding, just need to do page switching.
 */
static void copy_compressed_segment(struct compressed_bio *cb,
                                    char *dest, u32 len, u32 *cur_in)
{
        u32 orig_in = *cur_in;

        while (*cur_in < orig_in + len) {
                struct folio *cur_folio;
                u32 copy_len = min_t(u32, PAGE_SIZE - offset_in_page(*cur_in),
                                          orig_in + len - *cur_in);

                ASSERT(copy_len);
                cur_folio = cb->compressed_folios[*cur_in / PAGE_SIZE];

                memcpy_from_folio(dest + *cur_in - orig_in, cur_folio,
                                  offset_in_folio(cur_folio, *cur_in), copy_len);

                *cur_in += copy_len;
        }
}

int lzo_decompress_bio(struct list_head *ws, struct compressed_bio *cb)
{
        struct workspace *workspace = list_entry(ws, struct workspace, list);
        const struct btrfs_fs_info *fs_info = cb->bbio.inode->root->fs_info;
        const u32 sectorsize = fs_info->sectorsize;
        char *kaddr;
        int ret;
        /* Compressed data length, can be unaligned */
        u32 len_in;
        /* Offset inside the compressed data */
        u32 cur_in = 0;
        /* Bytes decompressed so far */
        u32 cur_out = 0;

        kaddr = kmap_local_folio(cb->compressed_folios[0], 0);
        len_in = read_compress_length(kaddr);
        kunmap_local(kaddr);
        cur_in += LZO_LEN;

        /*
         * LZO header length check
         *
         * The total length should not exceed the maximum extent length,
         * and all sectors should be used.
         * If this happens, it means the compressed extent is corrupted.
         */
        if (unlikely(len_in > min_t(size_t, BTRFS_MAX_COMPRESSED, cb->compressed_len) ||
                     round_up(len_in, sectorsize) < cb->compressed_len)) {
                struct btrfs_inode *inode = cb->bbio.inode;

                btrfs_err(fs_info,
"lzo header invalid, root %llu inode %llu offset %llu lzo len %u compressed len %u",
                          btrfs_root_id(inode->root), btrfs_ino(inode),
                          cb->start, len_in, cb->compressed_len);
                return -EUCLEAN;
        }

        /* Go through each lzo segment */
        while (cur_in < len_in) {
                struct folio *cur_folio;
                /* Length of the compressed segment */
                u32 seg_len;
                u32 sector_bytes_left;
                size_t out_len = lzo1x_worst_compress(sectorsize);

                /*
                 * We should always have enough space for one segment header
                 * inside current sector.
                 */
                ASSERT(cur_in / sectorsize ==
                       (cur_in + LZO_LEN - 1) / sectorsize);
                cur_folio = cb->compressed_folios[cur_in / PAGE_SIZE];
                ASSERT(cur_folio);
                kaddr = kmap_local_folio(cur_folio, 0);
                seg_len = read_compress_length(kaddr + offset_in_page(cur_in));
                kunmap_local(kaddr);
                cur_in += LZO_LEN;

                if (unlikely(seg_len > WORKSPACE_CBUF_LENGTH)) {
                        struct btrfs_inode *inode = cb->bbio.inode;

                        /*
                         * seg_len shouldn't be larger than we have allocated
                         * for workspace->cbuf
                         */
                        btrfs_err(fs_info,
                        "lzo segment too big, root %llu inode %llu offset %llu len %u",
                                  btrfs_root_id(inode->root), btrfs_ino(inode),
                                  cb->start, seg_len);
                        return -EIO;
                }

                /* Copy the compressed segment payload into workspace */
                copy_compressed_segment(cb, workspace->cbuf, seg_len, &cur_in);

                /* Decompress the data */
                ret = lzo1x_decompress_safe(workspace->cbuf, seg_len,
                                            workspace->buf, &out_len);
                if (unlikely(ret != LZO_E_OK)) {
                        struct btrfs_inode *inode = cb->bbio.inode;

                        btrfs_err(fs_info,
                "lzo decompression failed, error %d root %llu inode %llu offset %llu",
                                  ret, btrfs_root_id(inode->root), btrfs_ino(inode),
                                  cb->start);
                        return -EIO;
                }

                /* Copy the data into inode pages */
                ret = btrfs_decompress_buf2page(workspace->buf, out_len, cb, cur_out);
                cur_out += out_len;

                /* All data read, exit */
                if (ret == 0)
                        return 0;
                ret = 0;

                /* Check if the sector has enough space for a segment header */
                sector_bytes_left = sectorsize - (cur_in % sectorsize);
                if (sector_bytes_left >= LZO_LEN)
                        continue;

                /* Skip the padding zeros */
                cur_in += sector_bytes_left;
        }

        return 0;
}

int lzo_decompress(struct list_head *ws, const u8 *data_in,
                struct folio *dest_folio, unsigned long dest_pgoff, size_t srclen,
                size_t destlen)
{
        struct workspace *workspace = list_entry(ws, struct workspace, list);
        struct btrfs_fs_info *fs_info = folio_to_fs_info(dest_folio);
        const u32 sectorsize = fs_info->sectorsize;
        size_t in_len;
        size_t out_len;
        size_t max_segment_len = WORKSPACE_BUF_LENGTH;
        int ret = 0;

        if (srclen < LZO_LEN || srclen > max_segment_len + LZO_LEN * 2)
                return -EUCLEAN;

        in_len = read_compress_length(data_in);
        if (in_len != srclen)
                return -EUCLEAN;
        data_in += LZO_LEN;

        in_len = read_compress_length(data_in);
        if (in_len != srclen - LZO_LEN * 2) {
                ret = -EUCLEAN;
                goto out;
        }
        data_in += LZO_LEN;

        out_len = sectorsize;
        ret = lzo1x_decompress_safe(data_in, in_len, workspace->buf, &out_len);
        if (unlikely(ret != LZO_E_OK)) {
                struct btrfs_inode *inode = folio_to_inode(dest_folio);

                btrfs_err(fs_info,
                "lzo decompression failed, error %d root %llu inode %llu offset %llu",
                          ret, btrfs_root_id(inode->root), btrfs_ino(inode),
                          folio_pos(dest_folio));
                ret = -EIO;
                goto out;
        }

        ASSERT(out_len <= sectorsize);
        memcpy_to_folio(dest_folio, dest_pgoff, workspace->buf, out_len);
        /* Early end, considered as an error. */
        if (unlikely(out_len < destlen)) {
                ret = -EIO;
                folio_zero_range(dest_folio, dest_pgoff + out_len, destlen - out_len);
        }
out:
        return ret;
}

const struct btrfs_compress_op btrfs_lzo_compress = {
        .workspace_manager      = &wsm,
        .max_level              = 1,
        .default_level          = 1,
};