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950 lines
28 KiB
950 lines
28 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/** |
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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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|
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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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|
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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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/** |
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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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|
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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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/* |
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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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/** |
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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; |
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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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/** |
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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_SHIFT) >= initialized_size) { |
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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_MASK; |
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memset(kp + kp_ofs, 0, PAGE_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_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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* @completed_pages: scratch space to track completed 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_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 completed_pages[], |
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int *dest_index, int *dest_ofs, const int dest_max_index, |
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const int dest_max_ofs, const int xpage, char *xpage_done, |
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u8 *const cb_start, 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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|
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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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|
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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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int nr_completed_pages = 0; |
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|
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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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put_page(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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|
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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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|
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/* Advance destination position to next sub-block. */ |
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*dest_ofs = (*dest_ofs + NTFS_SB_SIZE) & ~PAGE_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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|
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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_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_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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|
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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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|
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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_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_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 |
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* initialized_size is less than data_size. This should be safe because of the |
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* nature of the compression algorithm used. Just in case we check and output |
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* an error message in read inode if the two sizes are not equal for a |
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* compressed file. (AIA) |
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*/ |
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int ntfs_read_compressed_block(struct page *page) |
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{ |
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loff_t i_size; |
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s64 initialized_size; |
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struct address_space *mapping = page->mapping; |
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ntfs_inode *ni = NTFS_I(mapping->host); |
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ntfs_volume *vol = ni->vol; |
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struct super_block *sb = vol->sb; |
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runlist_element *rl; |
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unsigned long flags, block_size = sb->s_blocksize; |
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unsigned char block_size_bits = sb->s_blocksize_bits; |
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u8 *cb, *cb_pos, *cb_end; |
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struct buffer_head **bhs; |
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unsigned long offset, index = page->index; |
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u32 cb_size = ni->itype.compressed.block_size; |
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u64 cb_size_mask = cb_size - 1UL; |
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VCN vcn; |
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LCN lcn; |
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/* The first wanted vcn (minimum alignment is PAGE_SIZE). */ |
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VCN start_vcn = (((s64)index << PAGE_SHIFT) & ~cb_size_mask) >> |
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vol->cluster_size_bits; |
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/* |
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* The first vcn after the last wanted vcn (minimum alignment is again |
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* PAGE_SIZE. |
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*/ |
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VCN end_vcn = ((((s64)(index + 1UL) << PAGE_SHIFT) + cb_size - 1) |
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& ~cb_size_mask) >> vol->cluster_size_bits; |
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/* Number of compression blocks (cbs) in the wanted vcn range. */ |
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unsigned int nr_cbs = (end_vcn - start_vcn) << vol->cluster_size_bits |
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>> ni->itype.compressed.block_size_bits; |
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/* |
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* Number of pages required to store the uncompressed data from all |
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* compression blocks (cbs) overlapping @page. Due to alignment |
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* guarantees of start_vcn and end_vcn, no need to round up here. |
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*/ |
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unsigned int nr_pages = (end_vcn - start_vcn) << |
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vol->cluster_size_bits >> PAGE_SHIFT; |
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unsigned int xpage, max_page, cur_page, cur_ofs, i; |
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unsigned int cb_clusters, cb_max_ofs; |
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int block, max_block, cb_max_page, bhs_size, nr_bhs, err = 0; |
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struct page **pages; |
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int *completed_pages; |
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unsigned char xpage_done = 0; |
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|
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ntfs_debug("Entering, page->index = 0x%lx, cb_size = 0x%x, nr_pages = " |
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"%i.", index, cb_size, nr_pages); |
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/* |
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* Bad things happen if we get here for anything that is not an |
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* unnamed $DATA attribute. |
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*/ |
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BUG_ON(ni->type != AT_DATA); |
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BUG_ON(ni->name_len); |
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|
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pages = kmalloc_array(nr_pages, sizeof(struct page *), GFP_NOFS); |
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completed_pages = kmalloc_array(nr_pages + 1, sizeof(int), GFP_NOFS); |
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|
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/* Allocate memory to store the buffer heads we need. */ |
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bhs_size = cb_size / block_size * sizeof(struct buffer_head *); |
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bhs = kmalloc(bhs_size, GFP_NOFS); |
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|
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if (unlikely(!pages || !bhs || !completed_pages)) { |
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kfree(bhs); |
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kfree(pages); |
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kfree(completed_pages); |
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unlock_page(page); |
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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_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_SIZE - 1) >> PAGE_SHIFT) - |
|
offset; |
|
/* Is the page fully outside i_size? (truncate in progress) */ |
|
if (xpage >= max_page) { |
|
kfree(bhs); |
|
kfree(pages); |
|
kfree(completed_pages); |
|
zero_user(page, 0, PAGE_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); |
|
put_page(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(REQ_OP_READ, 0, 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_SHIFT) + cur_ofs + cb_size; |
|
cb_max_ofs = cb_max_page & ~PAGE_MASK; |
|
cb_max_page >>= PAGE_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) { |
|
if (likely(!cur_ofs)) |
|
clear_page(page_address(page)); |
|
else |
|
memset(page_address(page) + cur_ofs, 0, |
|
PAGE_SIZE - |
|
cur_ofs); |
|
flush_dcache_page(page); |
|
kunmap(page); |
|
SetPageUptodate(page); |
|
unlock_page(page); |
|
if (cur_page == xpage) |
|
xpage_done = 1; |
|
else |
|
put_page(page); |
|
pages[cur_page] = NULL; |
|
} |
|
cb_pos += PAGE_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_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_SIZE - cur_ofs); |
|
cb_pos += PAGE_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 |
|
put_page(page); |
|
pages[cur2_page] = NULL; |
|
} |
|
cb_pos2 += PAGE_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, completed_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) |
|
put_page(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) |
|
put_page(page); |
|
pages[cur_page] = NULL; |
|
} |
|
} |
|
|
|
/* We no longer need the list of pages. */ |
|
kfree(pages); |
|
kfree(completed_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) |
|
put_page(page); |
|
} |
|
} |
|
kfree(pages); |
|
kfree(completed_pages); |
|
return -EIO; |
|
}
|
|
|