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![Omar Sandoval](/assets/img/avatar_default.png)
If btrfs_decompress_buf2page() is handed a bio with its page in the
middle of the working buffer, then we adjust the offset into the working
buffer. After we copy into the bio, we advance the iterator by the
number of bytes we copied. Then, we have some logic to handle the case
of discontiguous pages and adjust the offset into the working buffer
again. However, if we didn't advance the bio to a new page, we may enter
this case in error, essentially repeating the adjustment that we already
made when we entered the function. The end result is bogus data in the
bio.
Previously, we only checked for this case when we advanced to a new
page, but the conversion to bio iterators changed that. This restores
the old, correct behavior.
A case I saw when testing with zlib was:
buf_start = 42769
total_out = 46865
working_bytes = total_out - buf_start = 4096
start_byte = 45056
The condition (total_out > start_byte && buf_start < start_byte) is
true, so we adjust the offset:
buf_offset = start_byte - buf_start = 2287
working_bytes -= buf_offset = 1809
current_buf_start = buf_start = 42769
Then, we copy
bytes = min(bvec.bv_len, PAGE_SIZE - buf_offset, working_bytes) = 1809
buf_offset += bytes = 4096
working_bytes -= bytes = 0
current_buf_start += bytes = 44578
After bio_advance(), we are still in the same page, so start_byte is the
same. Then, we check (total_out > start_byte && current_buf_start < start_byte),
which is true! So, we adjust the values again:
buf_offset = start_byte - buf_start = 2287
working_bytes = total_out - start_byte = 1809
current_buf_start = buf_start + buf_offset = 45056
But note that working_bytes was already zero before this, so we should
have stopped copying.
Fixes: 974b1adc3b
("btrfs: use bio iterators for the decompression handlers")
Reported-by: Pat Erley <pat-lkml@erley.org>
Reviewed-by: Chris Mason <clm@fb.com>
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Tested-by: Liu Bo <bo.li.liu@oracle.com>
1107 lines
28 KiB
C
1107 lines
28 KiB
C
/*
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* Copyright (C) 2008 Oracle. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License v2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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#include <linux/kernel.h>
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#include <linux/bio.h>
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#include <linux/buffer_head.h>
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#include <linux/file.h>
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#include <linux/fs.h>
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#include <linux/pagemap.h>
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#include <linux/highmem.h>
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#include <linux/time.h>
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#include <linux/init.h>
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#include <linux/string.h>
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#include <linux/backing-dev.h>
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#include <linux/mpage.h>
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#include <linux/swap.h>
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#include <linux/writeback.h>
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#include <linux/bit_spinlock.h>
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#include <linux/slab.h>
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#include "ctree.h"
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#include "disk-io.h"
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#include "transaction.h"
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#include "btrfs_inode.h"
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#include "volumes.h"
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#include "ordered-data.h"
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#include "compression.h"
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#include "extent_io.h"
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#include "extent_map.h"
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struct compressed_bio {
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/* number of bios pending for this compressed extent */
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atomic_t pending_bios;
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/* the pages with the compressed data on them */
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struct page **compressed_pages;
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/* inode that owns this data */
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struct inode *inode;
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/* starting offset in the inode for our pages */
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u64 start;
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/* number of bytes in the inode we're working on */
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unsigned long len;
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/* number of bytes on disk */
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unsigned long compressed_len;
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/* the compression algorithm for this bio */
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int compress_type;
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/* number of compressed pages in the array */
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unsigned long nr_pages;
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/* IO errors */
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int errors;
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int mirror_num;
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/* for reads, this is the bio we are copying the data into */
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struct bio *orig_bio;
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/*
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* the start of a variable length array of checksums only
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* used by reads
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*/
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u32 sums;
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};
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static int btrfs_decompress_bio(int type, struct page **pages_in,
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u64 disk_start, struct bio *orig_bio,
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size_t srclen);
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static inline int compressed_bio_size(struct btrfs_fs_info *fs_info,
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unsigned long disk_size)
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{
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u16 csum_size = btrfs_super_csum_size(fs_info->super_copy);
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return sizeof(struct compressed_bio) +
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(DIV_ROUND_UP(disk_size, fs_info->sectorsize)) * csum_size;
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}
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static struct bio *compressed_bio_alloc(struct block_device *bdev,
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u64 first_byte, gfp_t gfp_flags)
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{
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return btrfs_bio_alloc(bdev, first_byte >> 9, BIO_MAX_PAGES, gfp_flags);
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}
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static int check_compressed_csum(struct inode *inode,
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struct compressed_bio *cb,
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u64 disk_start)
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{
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int ret;
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struct page *page;
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unsigned long i;
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char *kaddr;
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u32 csum;
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u32 *cb_sum = &cb->sums;
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if (BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)
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return 0;
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for (i = 0; i < cb->nr_pages; i++) {
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page = cb->compressed_pages[i];
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csum = ~(u32)0;
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kaddr = kmap_atomic(page);
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csum = btrfs_csum_data(kaddr, csum, PAGE_SIZE);
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btrfs_csum_final(csum, (u8 *)&csum);
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kunmap_atomic(kaddr);
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if (csum != *cb_sum) {
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btrfs_info(BTRFS_I(inode)->root->fs_info,
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"csum failed ino %llu extent %llu csum %u wanted %u mirror %d",
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btrfs_ino(inode), disk_start, csum, *cb_sum,
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cb->mirror_num);
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ret = -EIO;
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goto fail;
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}
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cb_sum++;
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}
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ret = 0;
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fail:
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return ret;
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}
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/* when we finish reading compressed pages from the disk, we
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* decompress them and then run the bio end_io routines on the
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* decompressed pages (in the inode address space).
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*
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* This allows the checksumming and other IO error handling routines
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* to work normally
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*
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* The compressed pages are freed here, and it must be run
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* in process context
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*/
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static void end_compressed_bio_read(struct bio *bio)
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{
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struct compressed_bio *cb = bio->bi_private;
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struct inode *inode;
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struct page *page;
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unsigned long index;
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int ret;
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if (bio->bi_error)
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cb->errors = 1;
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/* if there are more bios still pending for this compressed
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* extent, just exit
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*/
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if (!atomic_dec_and_test(&cb->pending_bios))
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goto out;
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inode = cb->inode;
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ret = check_compressed_csum(inode, cb,
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(u64)bio->bi_iter.bi_sector << 9);
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if (ret)
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goto csum_failed;
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/* ok, we're the last bio for this extent, lets start
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* the decompression.
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*/
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ret = btrfs_decompress_bio(cb->compress_type,
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cb->compressed_pages,
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cb->start,
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cb->orig_bio,
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cb->compressed_len);
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csum_failed:
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if (ret)
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cb->errors = 1;
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/* release the compressed pages */
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index = 0;
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for (index = 0; index < cb->nr_pages; index++) {
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page = cb->compressed_pages[index];
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page->mapping = NULL;
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put_page(page);
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}
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/* do io completion on the original bio */
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if (cb->errors) {
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bio_io_error(cb->orig_bio);
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} else {
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int i;
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struct bio_vec *bvec;
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/*
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* we have verified the checksum already, set page
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* checked so the end_io handlers know about it
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*/
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bio_for_each_segment_all(bvec, cb->orig_bio, i)
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SetPageChecked(bvec->bv_page);
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bio_endio(cb->orig_bio);
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}
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/* finally free the cb struct */
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kfree(cb->compressed_pages);
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kfree(cb);
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out:
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bio_put(bio);
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}
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/*
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* Clear the writeback bits on all of the file
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* pages for a compressed write
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*/
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static noinline void end_compressed_writeback(struct inode *inode,
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const struct compressed_bio *cb)
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{
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unsigned long index = cb->start >> PAGE_SHIFT;
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unsigned long end_index = (cb->start + cb->len - 1) >> PAGE_SHIFT;
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struct page *pages[16];
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unsigned long nr_pages = end_index - index + 1;
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int i;
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int ret;
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if (cb->errors)
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mapping_set_error(inode->i_mapping, -EIO);
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while (nr_pages > 0) {
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ret = find_get_pages_contig(inode->i_mapping, index,
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min_t(unsigned long,
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nr_pages, ARRAY_SIZE(pages)), pages);
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if (ret == 0) {
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nr_pages -= 1;
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index += 1;
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continue;
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}
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for (i = 0; i < ret; i++) {
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if (cb->errors)
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SetPageError(pages[i]);
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end_page_writeback(pages[i]);
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put_page(pages[i]);
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}
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nr_pages -= ret;
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index += ret;
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}
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/* the inode may be gone now */
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}
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/*
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* do the cleanup once all the compressed pages hit the disk.
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* This will clear writeback on the file pages and free the compressed
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* pages.
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*
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* This also calls the writeback end hooks for the file pages so that
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* metadata and checksums can be updated in the file.
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*/
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static void end_compressed_bio_write(struct bio *bio)
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{
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struct extent_io_tree *tree;
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struct compressed_bio *cb = bio->bi_private;
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struct inode *inode;
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struct page *page;
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unsigned long index;
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if (bio->bi_error)
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cb->errors = 1;
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|
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/* if there are more bios still pending for this compressed
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* extent, just exit
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*/
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if (!atomic_dec_and_test(&cb->pending_bios))
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goto out;
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/* ok, we're the last bio for this extent, step one is to
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* call back into the FS and do all the end_io operations
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*/
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inode = cb->inode;
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tree = &BTRFS_I(inode)->io_tree;
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cb->compressed_pages[0]->mapping = cb->inode->i_mapping;
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tree->ops->writepage_end_io_hook(cb->compressed_pages[0],
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cb->start,
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cb->start + cb->len - 1,
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NULL,
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bio->bi_error ? 0 : 1);
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cb->compressed_pages[0]->mapping = NULL;
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end_compressed_writeback(inode, cb);
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/* note, our inode could be gone now */
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/*
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* release the compressed pages, these came from alloc_page and
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* are not attached to the inode at all
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*/
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index = 0;
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for (index = 0; index < cb->nr_pages; index++) {
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page = cb->compressed_pages[index];
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page->mapping = NULL;
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put_page(page);
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}
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/* finally free the cb struct */
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kfree(cb->compressed_pages);
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kfree(cb);
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out:
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bio_put(bio);
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}
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/*
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* worker function to build and submit bios for previously compressed pages.
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* The corresponding pages in the inode should be marked for writeback
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* and the compressed pages should have a reference on them for dropping
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* when the IO is complete.
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*
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* This also checksums the file bytes and gets things ready for
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* the end io hooks.
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*/
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int btrfs_submit_compressed_write(struct inode *inode, u64 start,
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unsigned long len, u64 disk_start,
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unsigned long compressed_len,
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struct page **compressed_pages,
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unsigned long nr_pages)
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{
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struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
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struct bio *bio = NULL;
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struct compressed_bio *cb;
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unsigned long bytes_left;
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struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
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int pg_index = 0;
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struct page *page;
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u64 first_byte = disk_start;
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struct block_device *bdev;
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int ret;
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int skip_sum = BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM;
|
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WARN_ON(start & ((u64)PAGE_SIZE - 1));
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cb = kmalloc(compressed_bio_size(fs_info, compressed_len), GFP_NOFS);
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if (!cb)
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return -ENOMEM;
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atomic_set(&cb->pending_bios, 0);
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cb->errors = 0;
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cb->inode = inode;
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cb->start = start;
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cb->len = len;
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cb->mirror_num = 0;
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cb->compressed_pages = compressed_pages;
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cb->compressed_len = compressed_len;
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cb->orig_bio = NULL;
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cb->nr_pages = nr_pages;
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|
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bdev = fs_info->fs_devices->latest_bdev;
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|
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bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
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if (!bio) {
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kfree(cb);
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return -ENOMEM;
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}
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bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
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bio->bi_private = cb;
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bio->bi_end_io = end_compressed_bio_write;
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atomic_inc(&cb->pending_bios);
|
|
|
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/* create and submit bios for the compressed pages */
|
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bytes_left = compressed_len;
|
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for (pg_index = 0; pg_index < cb->nr_pages; pg_index++) {
|
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page = compressed_pages[pg_index];
|
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page->mapping = inode->i_mapping;
|
|
if (bio->bi_iter.bi_size)
|
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ret = io_tree->ops->merge_bio_hook(page, 0,
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PAGE_SIZE,
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bio, 0);
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else
|
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ret = 0;
|
|
|
|
page->mapping = NULL;
|
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if (ret || bio_add_page(bio, page, PAGE_SIZE, 0) <
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PAGE_SIZE) {
|
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bio_get(bio);
|
|
|
|
/*
|
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* inc the count before we submit the bio so
|
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* we know the end IO handler won't happen before
|
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* we inc the count. Otherwise, the cb might get
|
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* freed before we're done setting it up
|
|
*/
|
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atomic_inc(&cb->pending_bios);
|
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ret = btrfs_bio_wq_end_io(fs_info, bio,
|
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BTRFS_WQ_ENDIO_DATA);
|
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BUG_ON(ret); /* -ENOMEM */
|
|
|
|
if (!skip_sum) {
|
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ret = btrfs_csum_one_bio(inode, bio, start, 1);
|
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BUG_ON(ret); /* -ENOMEM */
|
|
}
|
|
|
|
ret = btrfs_map_bio(fs_info, bio, 0, 1);
|
|
if (ret) {
|
|
bio->bi_error = ret;
|
|
bio_endio(bio);
|
|
}
|
|
|
|
bio_put(bio);
|
|
|
|
bio = compressed_bio_alloc(bdev, first_byte, GFP_NOFS);
|
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BUG_ON(!bio);
|
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bio_set_op_attrs(bio, REQ_OP_WRITE, 0);
|
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bio->bi_private = cb;
|
|
bio->bi_end_io = end_compressed_bio_write;
|
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bio_add_page(bio, page, PAGE_SIZE, 0);
|
|
}
|
|
if (bytes_left < PAGE_SIZE) {
|
|
btrfs_info(fs_info,
|
|
"bytes left %lu compress len %lu nr %lu",
|
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bytes_left, cb->compressed_len, cb->nr_pages);
|
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}
|
|
bytes_left -= PAGE_SIZE;
|
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first_byte += PAGE_SIZE;
|
|
cond_resched();
|
|
}
|
|
bio_get(bio);
|
|
|
|
ret = btrfs_bio_wq_end_io(fs_info, bio, BTRFS_WQ_ENDIO_DATA);
|
|
BUG_ON(ret); /* -ENOMEM */
|
|
|
|
if (!skip_sum) {
|
|
ret = btrfs_csum_one_bio(inode, bio, start, 1);
|
|
BUG_ON(ret); /* -ENOMEM */
|
|
}
|
|
|
|
ret = btrfs_map_bio(fs_info, bio, 0, 1);
|
|
if (ret) {
|
|
bio->bi_error = ret;
|
|
bio_endio(bio);
|
|
}
|
|
|
|
bio_put(bio);
|
|
return 0;
|
|
}
|
|
|
|
static u64 bio_end_offset(struct bio *bio)
|
|
{
|
|
struct bio_vec *last = &bio->bi_io_vec[bio->bi_vcnt - 1];
|
|
|
|
return page_offset(last->bv_page) + last->bv_len + last->bv_offset;
|
|
}
|
|
|
|
static noinline int add_ra_bio_pages(struct inode *inode,
|
|
u64 compressed_end,
|
|
struct compressed_bio *cb)
|
|
{
|
|
unsigned long end_index;
|
|
unsigned long pg_index;
|
|
u64 last_offset;
|
|
u64 isize = i_size_read(inode);
|
|
int ret;
|
|
struct page *page;
|
|
unsigned long nr_pages = 0;
|
|
struct extent_map *em;
|
|
struct address_space *mapping = inode->i_mapping;
|
|
struct extent_map_tree *em_tree;
|
|
struct extent_io_tree *tree;
|
|
u64 end;
|
|
int misses = 0;
|
|
|
|
last_offset = bio_end_offset(cb->orig_bio);
|
|
em_tree = &BTRFS_I(inode)->extent_tree;
|
|
tree = &BTRFS_I(inode)->io_tree;
|
|
|
|
if (isize == 0)
|
|
return 0;
|
|
|
|
end_index = (i_size_read(inode) - 1) >> PAGE_SHIFT;
|
|
|
|
while (last_offset < compressed_end) {
|
|
pg_index = last_offset >> PAGE_SHIFT;
|
|
|
|
if (pg_index > end_index)
|
|
break;
|
|
|
|
rcu_read_lock();
|
|
page = radix_tree_lookup(&mapping->page_tree, pg_index);
|
|
rcu_read_unlock();
|
|
if (page && !radix_tree_exceptional_entry(page)) {
|
|
misses++;
|
|
if (misses > 4)
|
|
break;
|
|
goto next;
|
|
}
|
|
|
|
page = __page_cache_alloc(mapping_gfp_constraint(mapping,
|
|
~__GFP_FS));
|
|
if (!page)
|
|
break;
|
|
|
|
if (add_to_page_cache_lru(page, mapping, pg_index, GFP_NOFS)) {
|
|
put_page(page);
|
|
goto next;
|
|
}
|
|
|
|
end = last_offset + PAGE_SIZE - 1;
|
|
/*
|
|
* at this point, we have a locked page in the page cache
|
|
* for these bytes in the file. But, we have to make
|
|
* sure they map to this compressed extent on disk.
|
|
*/
|
|
set_page_extent_mapped(page);
|
|
lock_extent(tree, last_offset, end);
|
|
read_lock(&em_tree->lock);
|
|
em = lookup_extent_mapping(em_tree, last_offset,
|
|
PAGE_SIZE);
|
|
read_unlock(&em_tree->lock);
|
|
|
|
if (!em || last_offset < em->start ||
|
|
(last_offset + PAGE_SIZE > extent_map_end(em)) ||
|
|
(em->block_start >> 9) != cb->orig_bio->bi_iter.bi_sector) {
|
|
free_extent_map(em);
|
|
unlock_extent(tree, last_offset, end);
|
|
unlock_page(page);
|
|
put_page(page);
|
|
break;
|
|
}
|
|
free_extent_map(em);
|
|
|
|
if (page->index == end_index) {
|
|
char *userpage;
|
|
size_t zero_offset = isize & (PAGE_SIZE - 1);
|
|
|
|
if (zero_offset) {
|
|
int zeros;
|
|
zeros = PAGE_SIZE - zero_offset;
|
|
userpage = kmap_atomic(page);
|
|
memset(userpage + zero_offset, 0, zeros);
|
|
flush_dcache_page(page);
|
|
kunmap_atomic(userpage);
|
|
}
|
|
}
|
|
|
|
ret = bio_add_page(cb->orig_bio, page,
|
|
PAGE_SIZE, 0);
|
|
|
|
if (ret == PAGE_SIZE) {
|
|
nr_pages++;
|
|
put_page(page);
|
|
} else {
|
|
unlock_extent(tree, last_offset, end);
|
|
unlock_page(page);
|
|
put_page(page);
|
|
break;
|
|
}
|
|
next:
|
|
last_offset += PAGE_SIZE;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* for a compressed read, the bio we get passed has all the inode pages
|
|
* in it. We don't actually do IO on those pages but allocate new ones
|
|
* to hold the compressed pages on disk.
|
|
*
|
|
* bio->bi_iter.bi_sector points to the compressed extent on disk
|
|
* bio->bi_io_vec points to all of the inode pages
|
|
*
|
|
* After the compressed pages are read, we copy the bytes into the
|
|
* bio we were passed and then call the bio end_io calls
|
|
*/
|
|
int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
|
|
int mirror_num, unsigned long bio_flags)
|
|
{
|
|
struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
|
|
struct extent_io_tree *tree;
|
|
struct extent_map_tree *em_tree;
|
|
struct compressed_bio *cb;
|
|
unsigned long compressed_len;
|
|
unsigned long nr_pages;
|
|
unsigned long pg_index;
|
|
struct page *page;
|
|
struct block_device *bdev;
|
|
struct bio *comp_bio;
|
|
u64 cur_disk_byte = (u64)bio->bi_iter.bi_sector << 9;
|
|
u64 em_len;
|
|
u64 em_start;
|
|
struct extent_map *em;
|
|
int ret = -ENOMEM;
|
|
int faili = 0;
|
|
u32 *sums;
|
|
|
|
tree = &BTRFS_I(inode)->io_tree;
|
|
em_tree = &BTRFS_I(inode)->extent_tree;
|
|
|
|
/* we need the actual starting offset of this extent in the file */
|
|
read_lock(&em_tree->lock);
|
|
em = lookup_extent_mapping(em_tree,
|
|
page_offset(bio->bi_io_vec->bv_page),
|
|
PAGE_SIZE);
|
|
read_unlock(&em_tree->lock);
|
|
if (!em)
|
|
return -EIO;
|
|
|
|
compressed_len = em->block_len;
|
|
cb = kmalloc(compressed_bio_size(fs_info, compressed_len), GFP_NOFS);
|
|
if (!cb)
|
|
goto out;
|
|
|
|
atomic_set(&cb->pending_bios, 0);
|
|
cb->errors = 0;
|
|
cb->inode = inode;
|
|
cb->mirror_num = mirror_num;
|
|
sums = &cb->sums;
|
|
|
|
cb->start = em->orig_start;
|
|
em_len = em->len;
|
|
em_start = em->start;
|
|
|
|
free_extent_map(em);
|
|
em = NULL;
|
|
|
|
cb->len = bio->bi_iter.bi_size;
|
|
cb->compressed_len = compressed_len;
|
|
cb->compress_type = extent_compress_type(bio_flags);
|
|
cb->orig_bio = bio;
|
|
|
|
nr_pages = DIV_ROUND_UP(compressed_len, PAGE_SIZE);
|
|
cb->compressed_pages = kcalloc(nr_pages, sizeof(struct page *),
|
|
GFP_NOFS);
|
|
if (!cb->compressed_pages)
|
|
goto fail1;
|
|
|
|
bdev = fs_info->fs_devices->latest_bdev;
|
|
|
|
for (pg_index = 0; pg_index < nr_pages; pg_index++) {
|
|
cb->compressed_pages[pg_index] = alloc_page(GFP_NOFS |
|
|
__GFP_HIGHMEM);
|
|
if (!cb->compressed_pages[pg_index]) {
|
|
faili = pg_index - 1;
|
|
ret = -ENOMEM;
|
|
goto fail2;
|
|
}
|
|
}
|
|
faili = nr_pages - 1;
|
|
cb->nr_pages = nr_pages;
|
|
|
|
add_ra_bio_pages(inode, em_start + em_len, cb);
|
|
|
|
/* include any pages we added in add_ra-bio_pages */
|
|
cb->len = bio->bi_iter.bi_size;
|
|
|
|
comp_bio = compressed_bio_alloc(bdev, cur_disk_byte, GFP_NOFS);
|
|
if (!comp_bio)
|
|
goto fail2;
|
|
bio_set_op_attrs (comp_bio, REQ_OP_READ, 0);
|
|
comp_bio->bi_private = cb;
|
|
comp_bio->bi_end_io = end_compressed_bio_read;
|
|
atomic_inc(&cb->pending_bios);
|
|
|
|
for (pg_index = 0; pg_index < nr_pages; pg_index++) {
|
|
page = cb->compressed_pages[pg_index];
|
|
page->mapping = inode->i_mapping;
|
|
page->index = em_start >> PAGE_SHIFT;
|
|
|
|
if (comp_bio->bi_iter.bi_size)
|
|
ret = tree->ops->merge_bio_hook(page, 0,
|
|
PAGE_SIZE,
|
|
comp_bio, 0);
|
|
else
|
|
ret = 0;
|
|
|
|
page->mapping = NULL;
|
|
if (ret || bio_add_page(comp_bio, page, PAGE_SIZE, 0) <
|
|
PAGE_SIZE) {
|
|
bio_get(comp_bio);
|
|
|
|
ret = btrfs_bio_wq_end_io(fs_info, comp_bio,
|
|
BTRFS_WQ_ENDIO_DATA);
|
|
BUG_ON(ret); /* -ENOMEM */
|
|
|
|
/*
|
|
* inc the count before we submit the bio so
|
|
* we know the end IO handler won't happen before
|
|
* we inc the count. Otherwise, the cb might get
|
|
* freed before we're done setting it up
|
|
*/
|
|
atomic_inc(&cb->pending_bios);
|
|
|
|
if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
|
|
ret = btrfs_lookup_bio_sums(inode, comp_bio,
|
|
sums);
|
|
BUG_ON(ret); /* -ENOMEM */
|
|
}
|
|
sums += DIV_ROUND_UP(comp_bio->bi_iter.bi_size,
|
|
fs_info->sectorsize);
|
|
|
|
ret = btrfs_map_bio(fs_info, comp_bio, mirror_num, 0);
|
|
if (ret) {
|
|
comp_bio->bi_error = ret;
|
|
bio_endio(comp_bio);
|
|
}
|
|
|
|
bio_put(comp_bio);
|
|
|
|
comp_bio = compressed_bio_alloc(bdev, cur_disk_byte,
|
|
GFP_NOFS);
|
|
BUG_ON(!comp_bio);
|
|
bio_set_op_attrs(comp_bio, REQ_OP_READ, 0);
|
|
comp_bio->bi_private = cb;
|
|
comp_bio->bi_end_io = end_compressed_bio_read;
|
|
|
|
bio_add_page(comp_bio, page, PAGE_SIZE, 0);
|
|
}
|
|
cur_disk_byte += PAGE_SIZE;
|
|
}
|
|
bio_get(comp_bio);
|
|
|
|
ret = btrfs_bio_wq_end_io(fs_info, comp_bio, BTRFS_WQ_ENDIO_DATA);
|
|
BUG_ON(ret); /* -ENOMEM */
|
|
|
|
if (!(BTRFS_I(inode)->flags & BTRFS_INODE_NODATASUM)) {
|
|
ret = btrfs_lookup_bio_sums(inode, comp_bio, sums);
|
|
BUG_ON(ret); /* -ENOMEM */
|
|
}
|
|
|
|
ret = btrfs_map_bio(fs_info, comp_bio, mirror_num, 0);
|
|
if (ret) {
|
|
comp_bio->bi_error = ret;
|
|
bio_endio(comp_bio);
|
|
}
|
|
|
|
bio_put(comp_bio);
|
|
return 0;
|
|
|
|
fail2:
|
|
while (faili >= 0) {
|
|
__free_page(cb->compressed_pages[faili]);
|
|
faili--;
|
|
}
|
|
|
|
kfree(cb->compressed_pages);
|
|
fail1:
|
|
kfree(cb);
|
|
out:
|
|
free_extent_map(em);
|
|
return ret;
|
|
}
|
|
|
|
static struct {
|
|
struct list_head idle_ws;
|
|
spinlock_t ws_lock;
|
|
/* Number of free workspaces */
|
|
int free_ws;
|
|
/* Total number of allocated workspaces */
|
|
atomic_t total_ws;
|
|
/* Waiters for a free workspace */
|
|
wait_queue_head_t ws_wait;
|
|
} btrfs_comp_ws[BTRFS_COMPRESS_TYPES];
|
|
|
|
static const struct btrfs_compress_op * const btrfs_compress_op[] = {
|
|
&btrfs_zlib_compress,
|
|
&btrfs_lzo_compress,
|
|
};
|
|
|
|
void __init btrfs_init_compress(void)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
|
|
struct list_head *workspace;
|
|
|
|
INIT_LIST_HEAD(&btrfs_comp_ws[i].idle_ws);
|
|
spin_lock_init(&btrfs_comp_ws[i].ws_lock);
|
|
atomic_set(&btrfs_comp_ws[i].total_ws, 0);
|
|
init_waitqueue_head(&btrfs_comp_ws[i].ws_wait);
|
|
|
|
/*
|
|
* Preallocate one workspace for each compression type so
|
|
* we can guarantee forward progress in the worst case
|
|
*/
|
|
workspace = btrfs_compress_op[i]->alloc_workspace();
|
|
if (IS_ERR(workspace)) {
|
|
pr_warn("BTRFS: cannot preallocate compression workspace, will try later\n");
|
|
} else {
|
|
atomic_set(&btrfs_comp_ws[i].total_ws, 1);
|
|
btrfs_comp_ws[i].free_ws = 1;
|
|
list_add(workspace, &btrfs_comp_ws[i].idle_ws);
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* This finds an available workspace or allocates a new one.
|
|
* If it's not possible to allocate a new one, waits until there's one.
|
|
* Preallocation makes a forward progress guarantees and we do not return
|
|
* errors.
|
|
*/
|
|
static struct list_head *find_workspace(int type)
|
|
{
|
|
struct list_head *workspace;
|
|
int cpus = num_online_cpus();
|
|
int idx = type - 1;
|
|
|
|
struct list_head *idle_ws = &btrfs_comp_ws[idx].idle_ws;
|
|
spinlock_t *ws_lock = &btrfs_comp_ws[idx].ws_lock;
|
|
atomic_t *total_ws = &btrfs_comp_ws[idx].total_ws;
|
|
wait_queue_head_t *ws_wait = &btrfs_comp_ws[idx].ws_wait;
|
|
int *free_ws = &btrfs_comp_ws[idx].free_ws;
|
|
again:
|
|
spin_lock(ws_lock);
|
|
if (!list_empty(idle_ws)) {
|
|
workspace = idle_ws->next;
|
|
list_del(workspace);
|
|
(*free_ws)--;
|
|
spin_unlock(ws_lock);
|
|
return workspace;
|
|
|
|
}
|
|
if (atomic_read(total_ws) > cpus) {
|
|
DEFINE_WAIT(wait);
|
|
|
|
spin_unlock(ws_lock);
|
|
prepare_to_wait(ws_wait, &wait, TASK_UNINTERRUPTIBLE);
|
|
if (atomic_read(total_ws) > cpus && !*free_ws)
|
|
schedule();
|
|
finish_wait(ws_wait, &wait);
|
|
goto again;
|
|
}
|
|
atomic_inc(total_ws);
|
|
spin_unlock(ws_lock);
|
|
|
|
workspace = btrfs_compress_op[idx]->alloc_workspace();
|
|
if (IS_ERR(workspace)) {
|
|
atomic_dec(total_ws);
|
|
wake_up(ws_wait);
|
|
|
|
/*
|
|
* Do not return the error but go back to waiting. There's a
|
|
* workspace preallocated for each type and the compression
|
|
* time is bounded so we get to a workspace eventually. This
|
|
* makes our caller's life easier.
|
|
*
|
|
* To prevent silent and low-probability deadlocks (when the
|
|
* initial preallocation fails), check if there are any
|
|
* workspaces at all.
|
|
*/
|
|
if (atomic_read(total_ws) == 0) {
|
|
static DEFINE_RATELIMIT_STATE(_rs,
|
|
/* once per minute */ 60 * HZ,
|
|
/* no burst */ 1);
|
|
|
|
if (__ratelimit(&_rs)) {
|
|
pr_warn("BTRFS: no compression workspaces, low memory, retrying\n");
|
|
}
|
|
}
|
|
goto again;
|
|
}
|
|
return workspace;
|
|
}
|
|
|
|
/*
|
|
* put a workspace struct back on the list or free it if we have enough
|
|
* idle ones sitting around
|
|
*/
|
|
static void free_workspace(int type, struct list_head *workspace)
|
|
{
|
|
int idx = type - 1;
|
|
struct list_head *idle_ws = &btrfs_comp_ws[idx].idle_ws;
|
|
spinlock_t *ws_lock = &btrfs_comp_ws[idx].ws_lock;
|
|
atomic_t *total_ws = &btrfs_comp_ws[idx].total_ws;
|
|
wait_queue_head_t *ws_wait = &btrfs_comp_ws[idx].ws_wait;
|
|
int *free_ws = &btrfs_comp_ws[idx].free_ws;
|
|
|
|
spin_lock(ws_lock);
|
|
if (*free_ws < num_online_cpus()) {
|
|
list_add(workspace, idle_ws);
|
|
(*free_ws)++;
|
|
spin_unlock(ws_lock);
|
|
goto wake;
|
|
}
|
|
spin_unlock(ws_lock);
|
|
|
|
btrfs_compress_op[idx]->free_workspace(workspace);
|
|
atomic_dec(total_ws);
|
|
wake:
|
|
/*
|
|
* Make sure counter is updated before we wake up waiters.
|
|
*/
|
|
smp_mb();
|
|
if (waitqueue_active(ws_wait))
|
|
wake_up(ws_wait);
|
|
}
|
|
|
|
/*
|
|
* cleanup function for module exit
|
|
*/
|
|
static void free_workspaces(void)
|
|
{
|
|
struct list_head *workspace;
|
|
int i;
|
|
|
|
for (i = 0; i < BTRFS_COMPRESS_TYPES; i++) {
|
|
while (!list_empty(&btrfs_comp_ws[i].idle_ws)) {
|
|
workspace = btrfs_comp_ws[i].idle_ws.next;
|
|
list_del(workspace);
|
|
btrfs_compress_op[i]->free_workspace(workspace);
|
|
atomic_dec(&btrfs_comp_ws[i].total_ws);
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* given an address space and start/len, compress the bytes.
|
|
*
|
|
* pages are allocated to hold the compressed result and stored
|
|
* in 'pages'
|
|
*
|
|
* out_pages is used to return the number of pages allocated. There
|
|
* may be pages allocated even if we return an error
|
|
*
|
|
* total_in is used to return the number of bytes actually read. It
|
|
* may be smaller then len if we had to exit early because we
|
|
* ran out of room in the pages array or because we cross the
|
|
* max_out threshold.
|
|
*
|
|
* total_out is used to return the total number of compressed bytes
|
|
*
|
|
* max_out tells us the max number of bytes that we're allowed to
|
|
* stuff into pages
|
|
*/
|
|
int btrfs_compress_pages(int type, struct address_space *mapping,
|
|
u64 start, unsigned long len,
|
|
struct page **pages,
|
|
unsigned long nr_dest_pages,
|
|
unsigned long *out_pages,
|
|
unsigned long *total_in,
|
|
unsigned long *total_out,
|
|
unsigned long max_out)
|
|
{
|
|
struct list_head *workspace;
|
|
int ret;
|
|
|
|
workspace = find_workspace(type);
|
|
|
|
ret = btrfs_compress_op[type-1]->compress_pages(workspace, mapping,
|
|
start, len, pages,
|
|
nr_dest_pages, out_pages,
|
|
total_in, total_out,
|
|
max_out);
|
|
free_workspace(type, workspace);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* pages_in is an array of pages with compressed data.
|
|
*
|
|
* disk_start is the starting logical offset of this array in the file
|
|
*
|
|
* orig_bio contains the pages from the file that we want to decompress into
|
|
*
|
|
* srclen is the number of bytes in pages_in
|
|
*
|
|
* The basic idea is that we have a bio that was created by readpages.
|
|
* The pages in the bio are for the uncompressed data, and they may not
|
|
* be contiguous. They all correspond to the range of bytes covered by
|
|
* the compressed extent.
|
|
*/
|
|
static int btrfs_decompress_bio(int type, struct page **pages_in,
|
|
u64 disk_start, struct bio *orig_bio,
|
|
size_t srclen)
|
|
{
|
|
struct list_head *workspace;
|
|
int ret;
|
|
|
|
workspace = find_workspace(type);
|
|
|
|
ret = btrfs_compress_op[type-1]->decompress_bio(workspace, pages_in,
|
|
disk_start, orig_bio,
|
|
srclen);
|
|
free_workspace(type, workspace);
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* a less complex decompression routine. Our compressed data fits in a
|
|
* single page, and we want to read a single page out of it.
|
|
* start_byte tells us the offset into the compressed data we're interested in
|
|
*/
|
|
int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,
|
|
unsigned long start_byte, size_t srclen, size_t destlen)
|
|
{
|
|
struct list_head *workspace;
|
|
int ret;
|
|
|
|
workspace = find_workspace(type);
|
|
|
|
ret = btrfs_compress_op[type-1]->decompress(workspace, data_in,
|
|
dest_page, start_byte,
|
|
srclen, destlen);
|
|
|
|
free_workspace(type, workspace);
|
|
return ret;
|
|
}
|
|
|
|
void btrfs_exit_compress(void)
|
|
{
|
|
free_workspaces();
|
|
}
|
|
|
|
/*
|
|
* Copy uncompressed data from working buffer to pages.
|
|
*
|
|
* buf_start is the byte offset we're of the start of our workspace buffer.
|
|
*
|
|
* total_out is the last byte of the buffer
|
|
*/
|
|
int btrfs_decompress_buf2page(char *buf, unsigned long buf_start,
|
|
unsigned long total_out, u64 disk_start,
|
|
struct bio *bio)
|
|
{
|
|
unsigned long buf_offset;
|
|
unsigned long current_buf_start;
|
|
unsigned long start_byte;
|
|
unsigned long prev_start_byte;
|
|
unsigned long working_bytes = total_out - buf_start;
|
|
unsigned long bytes;
|
|
char *kaddr;
|
|
struct bio_vec bvec = bio_iter_iovec(bio, bio->bi_iter);
|
|
|
|
/*
|
|
* start byte is the first byte of the page we're currently
|
|
* copying into relative to the start of the compressed data.
|
|
*/
|
|
start_byte = page_offset(bvec.bv_page) - disk_start;
|
|
|
|
/* we haven't yet hit data corresponding to this page */
|
|
if (total_out <= start_byte)
|
|
return 1;
|
|
|
|
/*
|
|
* the start of the data we care about is offset into
|
|
* the middle of our working buffer
|
|
*/
|
|
if (total_out > start_byte && buf_start < start_byte) {
|
|
buf_offset = start_byte - buf_start;
|
|
working_bytes -= buf_offset;
|
|
} else {
|
|
buf_offset = 0;
|
|
}
|
|
current_buf_start = buf_start;
|
|
|
|
/* copy bytes from the working buffer into the pages */
|
|
while (working_bytes > 0) {
|
|
bytes = min_t(unsigned long, bvec.bv_len,
|
|
PAGE_SIZE - buf_offset);
|
|
bytes = min(bytes, working_bytes);
|
|
|
|
kaddr = kmap_atomic(bvec.bv_page);
|
|
memcpy(kaddr + bvec.bv_offset, buf + buf_offset, bytes);
|
|
kunmap_atomic(kaddr);
|
|
flush_dcache_page(bvec.bv_page);
|
|
|
|
buf_offset += bytes;
|
|
working_bytes -= bytes;
|
|
current_buf_start += bytes;
|
|
|
|
/* check if we need to pick another page */
|
|
bio_advance(bio, bytes);
|
|
if (!bio->bi_iter.bi_size)
|
|
return 0;
|
|
bvec = bio_iter_iovec(bio, bio->bi_iter);
|
|
prev_start_byte = start_byte;
|
|
start_byte = page_offset(bvec.bv_page) - disk_start;
|
|
|
|
/*
|
|
* We need to make sure we're only adjusting
|
|
* our offset into compression working buffer when
|
|
* we're switching pages. Otherwise we can incorrectly
|
|
* keep copying when we were actually done.
|
|
*/
|
|
if (start_byte != prev_start_byte) {
|
|
/*
|
|
* make sure our new page is covered by this
|
|
* working buffer
|
|
*/
|
|
if (total_out <= start_byte)
|
|
return 1;
|
|
|
|
/*
|
|
* the next page in the biovec might not be adjacent
|
|
* to the last page, but it might still be found
|
|
* inside this working buffer. bump our offset pointer
|
|
*/
|
|
if (total_out > start_byte &&
|
|
current_buf_start < start_byte) {
|
|
buf_offset = start_byte - buf_start;
|
|
working_bytes = total_out - start_byte;
|
|
current_buf_start = buf_start + buf_offset;
|
|
}
|
|
}
|
|
}
|
|
|
|
return 1;
|
|
}
|