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Fixes generated by 'codespell' and manually reviewed. Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
970 lines
29 KiB
C
970 lines
29 KiB
C
/**
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* compress.c - NTFS kernel compressed attributes handling.
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* Part of the Linux-NTFS project.
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*
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* Copyright (c) 2001-2004 Anton Altaparmakov
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* Copyright (c) 2002 Richard Russon
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*
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* This program/include file is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as published
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* by the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program/include file is distributed in the hope that it will be
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* useful, but WITHOUT ANY WARRANTY; without even the implied warranty
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* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU 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 License
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* along with this program (in the main directory of the Linux-NTFS
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* distribution in the file COPYING); if not, write to the Free Software
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* Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <linux/fs.h>
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#include <linux/buffer_head.h>
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#include <linux/blkdev.h>
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#include <linux/vmalloc.h>
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#include <linux/slab.h>
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#include "attrib.h"
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#include "inode.h"
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#include "debug.h"
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#include "ntfs.h"
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/**
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* ntfs_compression_constants - enum of constants used in the compression code
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*/
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typedef enum {
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/* Token types and access mask. */
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NTFS_SYMBOL_TOKEN = 0,
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NTFS_PHRASE_TOKEN = 1,
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NTFS_TOKEN_MASK = 1,
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/* Compression sub-block constants. */
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NTFS_SB_SIZE_MASK = 0x0fff,
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NTFS_SB_SIZE = 0x1000,
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NTFS_SB_IS_COMPRESSED = 0x8000,
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/*
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* The maximum compression block size is by definition 16 * the cluster
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* size, with the maximum supported cluster size being 4kiB. Thus the
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* maximum compression buffer size is 64kiB, so we use this when
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* initializing the compression buffer.
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*/
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NTFS_MAX_CB_SIZE = 64 * 1024,
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} ntfs_compression_constants;
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/**
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* ntfs_compression_buffer - one buffer for the decompression engine
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*/
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static u8 *ntfs_compression_buffer = NULL;
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/**
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* ntfs_cb_lock - spinlock which protects ntfs_compression_buffer
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*/
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static DEFINE_SPINLOCK(ntfs_cb_lock);
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/**
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* allocate_compression_buffers - allocate the decompression buffers
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*
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* Caller has to hold the ntfs_lock mutex.
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*
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* Return 0 on success or -ENOMEM if the allocations failed.
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*/
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int allocate_compression_buffers(void)
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{
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BUG_ON(ntfs_compression_buffer);
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ntfs_compression_buffer = vmalloc(NTFS_MAX_CB_SIZE);
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if (!ntfs_compression_buffer)
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return -ENOMEM;
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return 0;
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}
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/**
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* free_compression_buffers - free the decompression buffers
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*
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* Caller has to hold the ntfs_lock mutex.
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*/
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void free_compression_buffers(void)
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{
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BUG_ON(!ntfs_compression_buffer);
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vfree(ntfs_compression_buffer);
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ntfs_compression_buffer = NULL;
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}
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/**
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* zero_partial_compressed_page - zero out of bounds compressed page region
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*/
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static void zero_partial_compressed_page(struct page *page,
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const s64 initialized_size)
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{
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u8 *kp = page_address(page);
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unsigned int kp_ofs;
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ntfs_debug("Zeroing page region outside initialized size.");
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if (((s64)page->index << PAGE_CACHE_SHIFT) >= initialized_size) {
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/*
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* FIXME: Using clear_page() will become wrong when we get
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* PAGE_CACHE_SIZE != PAGE_SIZE but for now there is no problem.
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*/
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clear_page(kp);
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return;
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}
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kp_ofs = initialized_size & ~PAGE_CACHE_MASK;
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memset(kp + kp_ofs, 0, PAGE_CACHE_SIZE - kp_ofs);
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return;
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}
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/**
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* handle_bounds_compressed_page - test for&handle out of bounds compressed page
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*/
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static inline void handle_bounds_compressed_page(struct page *page,
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const loff_t i_size, const s64 initialized_size)
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{
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if ((page->index >= (initialized_size >> PAGE_CACHE_SHIFT)) &&
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(initialized_size < i_size))
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zero_partial_compressed_page(page, initialized_size);
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return;
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}
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/**
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* ntfs_decompress - decompress a compression block into an array of pages
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* @dest_pages: destination array of pages
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* @dest_index: current index into @dest_pages (IN/OUT)
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* @dest_ofs: current offset within @dest_pages[@dest_index] (IN/OUT)
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* @dest_max_index: maximum index into @dest_pages (IN)
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* @dest_max_ofs: maximum offset within @dest_pages[@dest_max_index] (IN)
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* @xpage: the target page (-1 if none) (IN)
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* @xpage_done: set to 1 if xpage was completed successfully (IN/OUT)
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* @cb_start: compression block to decompress (IN)
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* @cb_size: size of compression block @cb_start in bytes (IN)
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* @i_size: file size when we started the read (IN)
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* @initialized_size: initialized file size when we started the read (IN)
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*
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* The caller must have disabled preemption. ntfs_decompress() reenables it when
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* the critical section is finished.
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*
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* This decompresses the compression block @cb_start into the array of
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* destination pages @dest_pages starting at index @dest_index into @dest_pages
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* and at offset @dest_pos into the page @dest_pages[@dest_index].
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*
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* When the page @dest_pages[@xpage] is completed, @xpage_done is set to 1.
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* If xpage is -1 or @xpage has not been completed, @xpage_done is not modified.
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*
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* @cb_start is a pointer to the compression block which needs decompressing
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* and @cb_size is the size of @cb_start in bytes (8-64kiB).
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*
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* Return 0 if success or -EOVERFLOW on error in the compressed stream.
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* @xpage_done indicates whether the target page (@dest_pages[@xpage]) was
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* completed during the decompression of the compression block (@cb_start).
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*
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* Warning: This function *REQUIRES* PAGE_CACHE_SIZE >= 4096 or it will blow up
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* unpredicatbly! You have been warned!
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*
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* Note to hackers: This function may not sleep until it has finished accessing
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* the compression block @cb_start as it is a per-CPU buffer.
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*/
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static int ntfs_decompress(struct page *dest_pages[], int *dest_index,
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int *dest_ofs, const int dest_max_index, const int dest_max_ofs,
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const int xpage, char *xpage_done, u8 *const cb_start,
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const u32 cb_size, const loff_t i_size,
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const s64 initialized_size)
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{
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/*
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* Pointers into the compressed data, i.e. the compression block (cb),
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* and the therein contained sub-blocks (sb).
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*/
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u8 *cb_end = cb_start + cb_size; /* End of cb. */
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u8 *cb = cb_start; /* Current position in cb. */
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u8 *cb_sb_start = cb; /* Beginning of the current sb in the cb. */
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u8 *cb_sb_end; /* End of current sb / beginning of next sb. */
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/* Variables for uncompressed data / destination. */
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struct page *dp; /* Current destination page being worked on. */
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u8 *dp_addr; /* Current pointer into dp. */
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u8 *dp_sb_start; /* Start of current sub-block in dp. */
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u8 *dp_sb_end; /* End of current sb in dp (dp_sb_start +
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NTFS_SB_SIZE). */
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u16 do_sb_start; /* @dest_ofs when starting this sub-block. */
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u16 do_sb_end; /* @dest_ofs of end of this sb (do_sb_start +
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NTFS_SB_SIZE). */
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/* Variables for tag and token parsing. */
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u8 tag; /* Current tag. */
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int token; /* Loop counter for the eight tokens in tag. */
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/* Need this because we can't sleep, so need two stages. */
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int completed_pages[dest_max_index - *dest_index + 1];
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int nr_completed_pages = 0;
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/* Default error code. */
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int err = -EOVERFLOW;
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ntfs_debug("Entering, cb_size = 0x%x.", cb_size);
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do_next_sb:
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ntfs_debug("Beginning sub-block at offset = 0x%zx in the cb.",
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cb - cb_start);
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/*
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* Have we reached the end of the compression block or the end of the
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* decompressed data? The latter can happen for example if the current
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* position in the compression block is one byte before its end so the
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* first two checks do not detect it.
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*/
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if (cb == cb_end || !le16_to_cpup((le16*)cb) ||
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(*dest_index == dest_max_index &&
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*dest_ofs == dest_max_ofs)) {
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int i;
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ntfs_debug("Completed. Returning success (0).");
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err = 0;
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return_error:
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/* We can sleep from now on, so we drop lock. */
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spin_unlock(&ntfs_cb_lock);
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/* Second stage: finalize completed pages. */
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if (nr_completed_pages > 0) {
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for (i = 0; i < nr_completed_pages; i++) {
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int di = completed_pages[i];
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dp = dest_pages[di];
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/*
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* If we are outside the initialized size, zero
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* the out of bounds page range.
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*/
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handle_bounds_compressed_page(dp, i_size,
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initialized_size);
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flush_dcache_page(dp);
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kunmap(dp);
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SetPageUptodate(dp);
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unlock_page(dp);
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if (di == xpage)
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*xpage_done = 1;
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else
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page_cache_release(dp);
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dest_pages[di] = NULL;
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}
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}
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return err;
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}
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/* Setup offsets for the current sub-block destination. */
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do_sb_start = *dest_ofs;
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do_sb_end = do_sb_start + NTFS_SB_SIZE;
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/* Check that we are still within allowed boundaries. */
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if (*dest_index == dest_max_index && do_sb_end > dest_max_ofs)
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goto return_overflow;
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/* Does the minimum size of a compressed sb overflow valid range? */
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if (cb + 6 > cb_end)
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goto return_overflow;
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/* Setup the current sub-block source pointers and validate range. */
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cb_sb_start = cb;
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cb_sb_end = cb_sb_start + (le16_to_cpup((le16*)cb) & NTFS_SB_SIZE_MASK)
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+ 3;
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if (cb_sb_end > cb_end)
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goto return_overflow;
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/* Get the current destination page. */
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dp = dest_pages[*dest_index];
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if (!dp) {
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/* No page present. Skip decompression of this sub-block. */
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cb = cb_sb_end;
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/* Advance destination position to next sub-block. */
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*dest_ofs = (*dest_ofs + NTFS_SB_SIZE) & ~PAGE_CACHE_MASK;
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if (!*dest_ofs && (++*dest_index > dest_max_index))
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goto return_overflow;
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goto do_next_sb;
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}
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/* We have a valid destination page. Setup the destination pointers. */
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dp_addr = (u8*)page_address(dp) + do_sb_start;
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/* Now, we are ready to process the current sub-block (sb). */
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if (!(le16_to_cpup((le16*)cb) & NTFS_SB_IS_COMPRESSED)) {
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ntfs_debug("Found uncompressed sub-block.");
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/* This sb is not compressed, just copy it into destination. */
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/* Advance source position to first data byte. */
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cb += 2;
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/* An uncompressed sb must be full size. */
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if (cb_sb_end - cb != NTFS_SB_SIZE)
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goto return_overflow;
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/* Copy the block and advance the source position. */
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memcpy(dp_addr, cb, NTFS_SB_SIZE);
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cb += NTFS_SB_SIZE;
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/* Advance destination position to next sub-block. */
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*dest_ofs += NTFS_SB_SIZE;
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if (!(*dest_ofs &= ~PAGE_CACHE_MASK)) {
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finalize_page:
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/*
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* First stage: add current page index to array of
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* completed pages.
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*/
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completed_pages[nr_completed_pages++] = *dest_index;
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if (++*dest_index > dest_max_index)
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goto return_overflow;
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}
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goto do_next_sb;
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}
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ntfs_debug("Found compressed sub-block.");
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/* This sb is compressed, decompress it into destination. */
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/* Setup destination pointers. */
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dp_sb_start = dp_addr;
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dp_sb_end = dp_sb_start + NTFS_SB_SIZE;
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/* Forward to the first tag in the sub-block. */
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cb += 2;
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do_next_tag:
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if (cb == cb_sb_end) {
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/* Check if the decompressed sub-block was not full-length. */
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if (dp_addr < dp_sb_end) {
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int nr_bytes = do_sb_end - *dest_ofs;
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ntfs_debug("Filling incomplete sub-block with "
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"zeroes.");
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/* Zero remainder and update destination position. */
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memset(dp_addr, 0, nr_bytes);
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*dest_ofs += nr_bytes;
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}
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/* We have finished the current sub-block. */
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if (!(*dest_ofs &= ~PAGE_CACHE_MASK))
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goto finalize_page;
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goto do_next_sb;
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}
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/* Check we are still in range. */
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if (cb > cb_sb_end || dp_addr > dp_sb_end)
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goto return_overflow;
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/* Get the next tag and advance to first token. */
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tag = *cb++;
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/* Parse the eight tokens described by the tag. */
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for (token = 0; token < 8; token++, tag >>= 1) {
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u16 lg, pt, length, max_non_overlap;
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register u16 i;
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u8 *dp_back_addr;
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/* Check if we are done / still in range. */
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if (cb >= cb_sb_end || dp_addr > dp_sb_end)
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break;
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/* Determine token type and parse appropriately.*/
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if ((tag & NTFS_TOKEN_MASK) == NTFS_SYMBOL_TOKEN) {
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/*
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* We have a symbol token, copy the symbol across, and
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* advance the source and destination positions.
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*/
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*dp_addr++ = *cb++;
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++*dest_ofs;
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/* Continue with the next token. */
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continue;
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}
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/*
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* We have a phrase token. Make sure it is not the first tag in
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* the sb as this is illegal and would confuse the code below.
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*/
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if (dp_addr == dp_sb_start)
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goto return_overflow;
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/*
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* Determine the number of bytes to go back (p) and the number
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* of bytes to copy (l). We use an optimized algorithm in which
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* we first calculate log2(current destination position in sb),
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* which allows determination of l and p in O(1) rather than
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* O(n). We just need an arch-optimized log2() function now.
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*/
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lg = 0;
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for (i = *dest_ofs - do_sb_start - 1; i >= 0x10; i >>= 1)
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lg++;
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/* Get the phrase token into i. */
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pt = le16_to_cpup((le16*)cb);
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/*
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* Calculate starting position of the byte sequence in
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* the destination using the fact that p = (pt >> (12 - lg)) + 1
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* and make sure we don't go too far back.
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*/
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dp_back_addr = dp_addr - (pt >> (12 - lg)) - 1;
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if (dp_back_addr < dp_sb_start)
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goto return_overflow;
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/* Now calculate the length of the byte sequence. */
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length = (pt & (0xfff >> lg)) + 3;
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/* Advance destination position and verify it is in range. */
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*dest_ofs += length;
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if (*dest_ofs > do_sb_end)
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goto return_overflow;
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/* The number of non-overlapping bytes. */
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max_non_overlap = dp_addr - dp_back_addr;
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if (length <= max_non_overlap) {
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/* The byte sequence doesn't overlap, just copy it. */
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memcpy(dp_addr, dp_back_addr, length);
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/* Advance destination pointer. */
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dp_addr += length;
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} else {
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/*
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* The byte sequence does overlap, copy non-overlapping
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* part and then do a slow byte by byte copy for the
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* overlapping part. Also, advance the destination
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* pointer.
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*/
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memcpy(dp_addr, dp_back_addr, max_non_overlap);
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dp_addr += max_non_overlap;
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dp_back_addr += max_non_overlap;
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length -= max_non_overlap;
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while (length--)
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*dp_addr++ = *dp_back_addr++;
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}
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/* Advance source position and continue with the next token. */
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cb += 2;
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}
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/* No tokens left in the current tag. Continue with the next tag. */
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goto do_next_tag;
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return_overflow:
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ntfs_error(NULL, "Failed. Returning -EOVERFLOW.");
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goto return_error;
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}
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/**
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* ntfs_read_compressed_block - read a compressed block into the page cache
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* @page: locked page in the compression block(s) we need to read
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*
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* When we are called the page has already been verified to be locked and the
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* attribute is known to be non-resident, not encrypted, but compressed.
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*
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* 1. Determine which compression block(s) @page is in.
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* 2. Get hold of all pages corresponding to this/these compression block(s).
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* 3. Read the (first) compression block.
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* 4. Decompress it into the corresponding pages.
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* 5. Throw the compressed data away and proceed to 3. for the next compression
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* block or return success if no more compression blocks left.
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*
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* Warning: We have to be careful what we do about existing pages. They might
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* have been written to so that we would lose data if we were to just overwrite
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* them with the out-of-date uncompressed data.
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*
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* FIXME: For PAGE_CACHE_SIZE > cb_size we are not doing the Right Thing(TM) at
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* the end of the file I think. We need to detect this case and zero the out
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* of bounds remainder of the page in question and mark it as handled. At the
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* moment we would just return -EIO on such a page. This bug will only become
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* apparent if pages are above 8kiB and the NTFS volume only uses 512 byte
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* clusters so is probably not going to be seen by anyone. Still this should
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* be fixed. (AIA)
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*
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* FIXME: Again for PAGE_CACHE_SIZE > cb_size we are screwing up both in
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* handling sparse and compressed cbs. (AIA)
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*
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* FIXME: At the moment we don't do any zeroing out in the case that
|
|
* initialized_size is less than data_size. This should be safe because of the
|
|
* nature of the compression algorithm used. Just in case we check and output
|
|
* an error message in read inode if the two sizes are not equal for a
|
|
* compressed file. (AIA)
|
|
*/
|
|
int ntfs_read_compressed_block(struct page *page)
|
|
{
|
|
loff_t i_size;
|
|
s64 initialized_size;
|
|
struct address_space *mapping = page->mapping;
|
|
ntfs_inode *ni = NTFS_I(mapping->host);
|
|
ntfs_volume *vol = ni->vol;
|
|
struct super_block *sb = vol->sb;
|
|
runlist_element *rl;
|
|
unsigned long flags, block_size = sb->s_blocksize;
|
|
unsigned char block_size_bits = sb->s_blocksize_bits;
|
|
u8 *cb, *cb_pos, *cb_end;
|
|
struct buffer_head **bhs;
|
|
unsigned long offset, index = page->index;
|
|
u32 cb_size = ni->itype.compressed.block_size;
|
|
u64 cb_size_mask = cb_size - 1UL;
|
|
VCN vcn;
|
|
LCN lcn;
|
|
/* The first wanted vcn (minimum alignment is PAGE_CACHE_SIZE). */
|
|
VCN start_vcn = (((s64)index << PAGE_CACHE_SHIFT) & ~cb_size_mask) >>
|
|
vol->cluster_size_bits;
|
|
/*
|
|
* The first vcn after the last wanted vcn (minimum alignment is again
|
|
* PAGE_CACHE_SIZE.
|
|
*/
|
|
VCN end_vcn = ((((s64)(index + 1UL) << PAGE_CACHE_SHIFT) + cb_size - 1)
|
|
& ~cb_size_mask) >> vol->cluster_size_bits;
|
|
/* Number of compression blocks (cbs) in the wanted vcn range. */
|
|
unsigned int nr_cbs = (end_vcn - start_vcn) << vol->cluster_size_bits
|
|
>> ni->itype.compressed.block_size_bits;
|
|
/*
|
|
* Number of pages required to store the uncompressed data from all
|
|
* compression blocks (cbs) overlapping @page. Due to alignment
|
|
* guarantees of start_vcn and end_vcn, no need to round up here.
|
|
*/
|
|
unsigned int nr_pages = (end_vcn - start_vcn) <<
|
|
vol->cluster_size_bits >> PAGE_CACHE_SHIFT;
|
|
unsigned int xpage, max_page, cur_page, cur_ofs, i;
|
|
unsigned int cb_clusters, cb_max_ofs;
|
|
int block, max_block, cb_max_page, bhs_size, nr_bhs, err = 0;
|
|
struct page **pages;
|
|
unsigned char xpage_done = 0;
|
|
|
|
ntfs_debug("Entering, page->index = 0x%lx, cb_size = 0x%x, nr_pages = "
|
|
"%i.", index, cb_size, nr_pages);
|
|
/*
|
|
* Bad things happen if we get here for anything that is not an
|
|
* unnamed $DATA attribute.
|
|
*/
|
|
BUG_ON(ni->type != AT_DATA);
|
|
BUG_ON(ni->name_len);
|
|
|
|
pages = kmalloc(nr_pages * sizeof(struct page *), GFP_NOFS);
|
|
|
|
/* Allocate memory to store the buffer heads we need. */
|
|
bhs_size = cb_size / block_size * sizeof(struct buffer_head *);
|
|
bhs = kmalloc(bhs_size, GFP_NOFS);
|
|
|
|
if (unlikely(!pages || !bhs)) {
|
|
kfree(bhs);
|
|
kfree(pages);
|
|
unlock_page(page);
|
|
ntfs_error(vol->sb, "Failed to allocate internal buffers.");
|
|
return -ENOMEM;
|
|
}
|
|
|
|
/*
|
|
* We have already been given one page, this is the one we must do.
|
|
* Once again, the alignment guarantees keep it simple.
|
|
*/
|
|
offset = start_vcn << vol->cluster_size_bits >> PAGE_CACHE_SHIFT;
|
|
xpage = index - offset;
|
|
pages[xpage] = page;
|
|
/*
|
|
* The remaining pages need to be allocated and inserted into the page
|
|
* cache, alignment guarantees keep all the below much simpler. (-8
|
|
*/
|
|
read_lock_irqsave(&ni->size_lock, flags);
|
|
i_size = i_size_read(VFS_I(ni));
|
|
initialized_size = ni->initialized_size;
|
|
read_unlock_irqrestore(&ni->size_lock, flags);
|
|
max_page = ((i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT) -
|
|
offset;
|
|
/* Is the page fully outside i_size? (truncate in progress) */
|
|
if (xpage >= max_page) {
|
|
kfree(bhs);
|
|
kfree(pages);
|
|
zero_user(page, 0, PAGE_CACHE_SIZE);
|
|
ntfs_debug("Compressed read outside i_size - truncated?");
|
|
SetPageUptodate(page);
|
|
unlock_page(page);
|
|
return 0;
|
|
}
|
|
if (nr_pages < max_page)
|
|
max_page = nr_pages;
|
|
for (i = 0; i < max_page; i++, offset++) {
|
|
if (i != xpage)
|
|
pages[i] = grab_cache_page_nowait(mapping, offset);
|
|
page = pages[i];
|
|
if (page) {
|
|
/*
|
|
* We only (re)read the page if it isn't already read
|
|
* in and/or dirty or we would be losing data or at
|
|
* least wasting our time.
|
|
*/
|
|
if (!PageDirty(page) && (!PageUptodate(page) ||
|
|
PageError(page))) {
|
|
ClearPageError(page);
|
|
kmap(page);
|
|
continue;
|
|
}
|
|
unlock_page(page);
|
|
page_cache_release(page);
|
|
pages[i] = NULL;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* We have the runlist, and all the destination pages we need to fill.
|
|
* Now read the first compression block.
|
|
*/
|
|
cur_page = 0;
|
|
cur_ofs = 0;
|
|
cb_clusters = ni->itype.compressed.block_clusters;
|
|
do_next_cb:
|
|
nr_cbs--;
|
|
nr_bhs = 0;
|
|
|
|
/* Read all cb buffer heads one cluster at a time. */
|
|
rl = NULL;
|
|
for (vcn = start_vcn, start_vcn += cb_clusters; vcn < start_vcn;
|
|
vcn++) {
|
|
bool is_retry = false;
|
|
|
|
if (!rl) {
|
|
lock_retry_remap:
|
|
down_read(&ni->runlist.lock);
|
|
rl = ni->runlist.rl;
|
|
}
|
|
if (likely(rl != NULL)) {
|
|
/* Seek to element containing target vcn. */
|
|
while (rl->length && rl[1].vcn <= vcn)
|
|
rl++;
|
|
lcn = ntfs_rl_vcn_to_lcn(rl, vcn);
|
|
} else
|
|
lcn = LCN_RL_NOT_MAPPED;
|
|
ntfs_debug("Reading vcn = 0x%llx, lcn = 0x%llx.",
|
|
(unsigned long long)vcn,
|
|
(unsigned long long)lcn);
|
|
if (lcn < 0) {
|
|
/*
|
|
* When we reach the first sparse cluster we have
|
|
* finished with the cb.
|
|
*/
|
|
if (lcn == LCN_HOLE)
|
|
break;
|
|
if (is_retry || lcn != LCN_RL_NOT_MAPPED)
|
|
goto rl_err;
|
|
is_retry = true;
|
|
/*
|
|
* Attempt to map runlist, dropping lock for the
|
|
* duration.
|
|
*/
|
|
up_read(&ni->runlist.lock);
|
|
if (!ntfs_map_runlist(ni, vcn))
|
|
goto lock_retry_remap;
|
|
goto map_rl_err;
|
|
}
|
|
block = lcn << vol->cluster_size_bits >> block_size_bits;
|
|
/* Read the lcn from device in chunks of block_size bytes. */
|
|
max_block = block + (vol->cluster_size >> block_size_bits);
|
|
do {
|
|
ntfs_debug("block = 0x%x.", block);
|
|
if (unlikely(!(bhs[nr_bhs] = sb_getblk(sb, block))))
|
|
goto getblk_err;
|
|
nr_bhs++;
|
|
} while (++block < max_block);
|
|
}
|
|
|
|
/* Release the lock if we took it. */
|
|
if (rl)
|
|
up_read(&ni->runlist.lock);
|
|
|
|
/* Setup and initiate io on all buffer heads. */
|
|
for (i = 0; i < nr_bhs; i++) {
|
|
struct buffer_head *tbh = bhs[i];
|
|
|
|
if (!trylock_buffer(tbh))
|
|
continue;
|
|
if (unlikely(buffer_uptodate(tbh))) {
|
|
unlock_buffer(tbh);
|
|
continue;
|
|
}
|
|
get_bh(tbh);
|
|
tbh->b_end_io = end_buffer_read_sync;
|
|
submit_bh(READ, tbh);
|
|
}
|
|
|
|
/* Wait for io completion on all buffer heads. */
|
|
for (i = 0; i < nr_bhs; i++) {
|
|
struct buffer_head *tbh = bhs[i];
|
|
|
|
if (buffer_uptodate(tbh))
|
|
continue;
|
|
wait_on_buffer(tbh);
|
|
/*
|
|
* We need an optimization barrier here, otherwise we start
|
|
* hitting the below fixup code when accessing a loopback
|
|
* mounted ntfs partition. This indicates either there is a
|
|
* race condition in the loop driver or, more likely, gcc
|
|
* overoptimises the code without the barrier and it doesn't
|
|
* do the Right Thing(TM).
|
|
*/
|
|
barrier();
|
|
if (unlikely(!buffer_uptodate(tbh))) {
|
|
ntfs_warning(vol->sb, "Buffer is unlocked but not "
|
|
"uptodate! Unplugging the disk queue "
|
|
"and rescheduling.");
|
|
get_bh(tbh);
|
|
io_schedule();
|
|
put_bh(tbh);
|
|
if (unlikely(!buffer_uptodate(tbh)))
|
|
goto read_err;
|
|
ntfs_warning(vol->sb, "Buffer is now uptodate. Good.");
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Get the compression buffer. We must not sleep any more
|
|
* until we are finished with it.
|
|
*/
|
|
spin_lock(&ntfs_cb_lock);
|
|
cb = ntfs_compression_buffer;
|
|
|
|
BUG_ON(!cb);
|
|
|
|
cb_pos = cb;
|
|
cb_end = cb + cb_size;
|
|
|
|
/* Copy the buffer heads into the contiguous buffer. */
|
|
for (i = 0; i < nr_bhs; i++) {
|
|
memcpy(cb_pos, bhs[i]->b_data, block_size);
|
|
cb_pos += block_size;
|
|
}
|
|
|
|
/* Just a precaution. */
|
|
if (cb_pos + 2 <= cb + cb_size)
|
|
*(u16*)cb_pos = 0;
|
|
|
|
/* Reset cb_pos back to the beginning. */
|
|
cb_pos = cb;
|
|
|
|
/* We now have both source (if present) and destination. */
|
|
ntfs_debug("Successfully read the compression block.");
|
|
|
|
/* The last page and maximum offset within it for the current cb. */
|
|
cb_max_page = (cur_page << PAGE_CACHE_SHIFT) + cur_ofs + cb_size;
|
|
cb_max_ofs = cb_max_page & ~PAGE_CACHE_MASK;
|
|
cb_max_page >>= PAGE_CACHE_SHIFT;
|
|
|
|
/* Catch end of file inside a compression block. */
|
|
if (cb_max_page > max_page)
|
|
cb_max_page = max_page;
|
|
|
|
if (vcn == start_vcn - cb_clusters) {
|
|
/* Sparse cb, zero out page range overlapping the cb. */
|
|
ntfs_debug("Found sparse compression block.");
|
|
/* We can sleep from now on, so we drop lock. */
|
|
spin_unlock(&ntfs_cb_lock);
|
|
if (cb_max_ofs)
|
|
cb_max_page--;
|
|
for (; cur_page < cb_max_page; cur_page++) {
|
|
page = pages[cur_page];
|
|
if (page) {
|
|
/*
|
|
* FIXME: Using clear_page() will become wrong
|
|
* when we get PAGE_CACHE_SIZE != PAGE_SIZE but
|
|
* for now there is no problem.
|
|
*/
|
|
if (likely(!cur_ofs))
|
|
clear_page(page_address(page));
|
|
else
|
|
memset(page_address(page) + cur_ofs, 0,
|
|
PAGE_CACHE_SIZE -
|
|
cur_ofs);
|
|
flush_dcache_page(page);
|
|
kunmap(page);
|
|
SetPageUptodate(page);
|
|
unlock_page(page);
|
|
if (cur_page == xpage)
|
|
xpage_done = 1;
|
|
else
|
|
page_cache_release(page);
|
|
pages[cur_page] = NULL;
|
|
}
|
|
cb_pos += PAGE_CACHE_SIZE - cur_ofs;
|
|
cur_ofs = 0;
|
|
if (cb_pos >= cb_end)
|
|
break;
|
|
}
|
|
/* If we have a partial final page, deal with it now. */
|
|
if (cb_max_ofs && cb_pos < cb_end) {
|
|
page = pages[cur_page];
|
|
if (page)
|
|
memset(page_address(page) + cur_ofs, 0,
|
|
cb_max_ofs - cur_ofs);
|
|
/*
|
|
* No need to update cb_pos at this stage:
|
|
* cb_pos += cb_max_ofs - cur_ofs;
|
|
*/
|
|
cur_ofs = cb_max_ofs;
|
|
}
|
|
} else if (vcn == start_vcn) {
|
|
/* We can't sleep so we need two stages. */
|
|
unsigned int cur2_page = cur_page;
|
|
unsigned int cur_ofs2 = cur_ofs;
|
|
u8 *cb_pos2 = cb_pos;
|
|
|
|
ntfs_debug("Found uncompressed compression block.");
|
|
/* Uncompressed cb, copy it to the destination pages. */
|
|
/*
|
|
* TODO: As a big optimization, we could detect this case
|
|
* before we read all the pages and use block_read_full_page()
|
|
* on all full pages instead (we still have to treat partial
|
|
* pages especially but at least we are getting rid of the
|
|
* synchronous io for the majority of pages.
|
|
* Or if we choose not to do the read-ahead/-behind stuff, we
|
|
* could just return block_read_full_page(pages[xpage]) as long
|
|
* as PAGE_CACHE_SIZE <= cb_size.
|
|
*/
|
|
if (cb_max_ofs)
|
|
cb_max_page--;
|
|
/* First stage: copy data into destination pages. */
|
|
for (; cur_page < cb_max_page; cur_page++) {
|
|
page = pages[cur_page];
|
|
if (page)
|
|
memcpy(page_address(page) + cur_ofs, cb_pos,
|
|
PAGE_CACHE_SIZE - cur_ofs);
|
|
cb_pos += PAGE_CACHE_SIZE - cur_ofs;
|
|
cur_ofs = 0;
|
|
if (cb_pos >= cb_end)
|
|
break;
|
|
}
|
|
/* If we have a partial final page, deal with it now. */
|
|
if (cb_max_ofs && cb_pos < cb_end) {
|
|
page = pages[cur_page];
|
|
if (page)
|
|
memcpy(page_address(page) + cur_ofs, cb_pos,
|
|
cb_max_ofs - cur_ofs);
|
|
cb_pos += cb_max_ofs - cur_ofs;
|
|
cur_ofs = cb_max_ofs;
|
|
}
|
|
/* We can sleep from now on, so drop lock. */
|
|
spin_unlock(&ntfs_cb_lock);
|
|
/* Second stage: finalize pages. */
|
|
for (; cur2_page < cb_max_page; cur2_page++) {
|
|
page = pages[cur2_page];
|
|
if (page) {
|
|
/*
|
|
* If we are outside the initialized size, zero
|
|
* the out of bounds page range.
|
|
*/
|
|
handle_bounds_compressed_page(page, i_size,
|
|
initialized_size);
|
|
flush_dcache_page(page);
|
|
kunmap(page);
|
|
SetPageUptodate(page);
|
|
unlock_page(page);
|
|
if (cur2_page == xpage)
|
|
xpage_done = 1;
|
|
else
|
|
page_cache_release(page);
|
|
pages[cur2_page] = NULL;
|
|
}
|
|
cb_pos2 += PAGE_CACHE_SIZE - cur_ofs2;
|
|
cur_ofs2 = 0;
|
|
if (cb_pos2 >= cb_end)
|
|
break;
|
|
}
|
|
} else {
|
|
/* Compressed cb, decompress it into the destination page(s). */
|
|
unsigned int prev_cur_page = cur_page;
|
|
|
|
ntfs_debug("Found compressed compression block.");
|
|
err = ntfs_decompress(pages, &cur_page, &cur_ofs,
|
|
cb_max_page, cb_max_ofs, xpage, &xpage_done,
|
|
cb_pos, cb_size - (cb_pos - cb), i_size,
|
|
initialized_size);
|
|
/*
|
|
* We can sleep from now on, lock already dropped by
|
|
* ntfs_decompress().
|
|
*/
|
|
if (err) {
|
|
ntfs_error(vol->sb, "ntfs_decompress() failed in inode "
|
|
"0x%lx with error code %i. Skipping "
|
|
"this compression block.",
|
|
ni->mft_no, -err);
|
|
/* Release the unfinished pages. */
|
|
for (; prev_cur_page < cur_page; prev_cur_page++) {
|
|
page = pages[prev_cur_page];
|
|
if (page) {
|
|
flush_dcache_page(page);
|
|
kunmap(page);
|
|
unlock_page(page);
|
|
if (prev_cur_page != xpage)
|
|
page_cache_release(page);
|
|
pages[prev_cur_page] = NULL;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Release the buffer heads. */
|
|
for (i = 0; i < nr_bhs; i++)
|
|
brelse(bhs[i]);
|
|
|
|
/* Do we have more work to do? */
|
|
if (nr_cbs)
|
|
goto do_next_cb;
|
|
|
|
/* We no longer need the list of buffer heads. */
|
|
kfree(bhs);
|
|
|
|
/* Clean up if we have any pages left. Should never happen. */
|
|
for (cur_page = 0; cur_page < max_page; cur_page++) {
|
|
page = pages[cur_page];
|
|
if (page) {
|
|
ntfs_error(vol->sb, "Still have pages left! "
|
|
"Terminating them with extreme "
|
|
"prejudice. Inode 0x%lx, page index "
|
|
"0x%lx.", ni->mft_no, page->index);
|
|
flush_dcache_page(page);
|
|
kunmap(page);
|
|
unlock_page(page);
|
|
if (cur_page != xpage)
|
|
page_cache_release(page);
|
|
pages[cur_page] = NULL;
|
|
}
|
|
}
|
|
|
|
/* We no longer need the list of pages. */
|
|
kfree(pages);
|
|
|
|
/* If we have completed the requested page, we return success. */
|
|
if (likely(xpage_done))
|
|
return 0;
|
|
|
|
ntfs_debug("Failed. Returning error code %s.", err == -EOVERFLOW ?
|
|
"EOVERFLOW" : (!err ? "EIO" : "unknown error"));
|
|
return err < 0 ? err : -EIO;
|
|
|
|
read_err:
|
|
ntfs_error(vol->sb, "IO error while reading compressed data.");
|
|
/* Release the buffer heads. */
|
|
for (i = 0; i < nr_bhs; i++)
|
|
brelse(bhs[i]);
|
|
goto err_out;
|
|
|
|
map_rl_err:
|
|
ntfs_error(vol->sb, "ntfs_map_runlist() failed. Cannot read "
|
|
"compression block.");
|
|
goto err_out;
|
|
|
|
rl_err:
|
|
up_read(&ni->runlist.lock);
|
|
ntfs_error(vol->sb, "ntfs_rl_vcn_to_lcn() failed. Cannot read "
|
|
"compression block.");
|
|
goto err_out;
|
|
|
|
getblk_err:
|
|
up_read(&ni->runlist.lock);
|
|
ntfs_error(vol->sb, "getblk() failed. Cannot read compression block.");
|
|
|
|
err_out:
|
|
kfree(bhs);
|
|
for (i = cur_page; i < max_page; i++) {
|
|
page = pages[i];
|
|
if (page) {
|
|
flush_dcache_page(page);
|
|
kunmap(page);
|
|
unlock_page(page);
|
|
if (i != xpage)
|
|
page_cache_release(page);
|
|
}
|
|
}
|
|
kfree(pages);
|
|
return -EIO;
|
|
}
|