/** * compress.c - NTFS kernel compressed attributes handling. * Part of the Linux-NTFS project. * * Copyright (c) 2001-2004 Anton Altaparmakov * Copyright (c) 2002 Richard Russon * * This program/include file is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License as published * by the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program/include file is distributed in the hope that it will be * useful, but WITHOUT ANY WARRANTY; without even the implied warranty * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program (in the main directory of the Linux-NTFS * distribution in the file COPYING); if not, write to the Free Software * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ #include <linux/fs.h> #include <linux/buffer_head.h> #include <linux/blkdev.h> #include <linux/vmalloc.h> #include <linux/slab.h> #include "attrib.h" #include "inode.h" #include "debug.h" #include "ntfs.h" /** * ntfs_compression_constants - enum of constants used in the compression code */ typedef enum { /* Token types and access mask. */ NTFS_SYMBOL_TOKEN = 0, NTFS_PHRASE_TOKEN = 1, NTFS_TOKEN_MASK = 1, /* Compression sub-block constants. */ NTFS_SB_SIZE_MASK = 0x0fff, NTFS_SB_SIZE = 0x1000, NTFS_SB_IS_COMPRESSED = 0x8000, /* * The maximum compression block size is by definition 16 * the cluster * size, with the maximum supported cluster size being 4kiB. Thus the * maximum compression buffer size is 64kiB, so we use this when * initializing the compression buffer. */ NTFS_MAX_CB_SIZE = 64 * 1024, } ntfs_compression_constants; /** * ntfs_compression_buffer - one buffer for the decompression engine */ static u8 *ntfs_compression_buffer; /** * ntfs_cb_lock - spinlock which protects ntfs_compression_buffer */ static DEFINE_SPINLOCK(ntfs_cb_lock); /** * allocate_compression_buffers - allocate the decompression buffers * * Caller has to hold the ntfs_lock mutex. * * Return 0 on success or -ENOMEM if the allocations failed. */ int allocate_compression_buffers(void) { BUG_ON(ntfs_compression_buffer); ntfs_compression_buffer = vmalloc(NTFS_MAX_CB_SIZE); if (!ntfs_compression_buffer) return -ENOMEM; return 0; } /** * free_compression_buffers - free the decompression buffers * * Caller has to hold the ntfs_lock mutex. */ void free_compression_buffers(void) { BUG_ON(!ntfs_compression_buffer); vfree(ntfs_compression_buffer); ntfs_compression_buffer = NULL; } /** * zero_partial_compressed_page - zero out of bounds compressed page region */ static void zero_partial_compressed_page(struct page *page, const s64 initialized_size) { u8 *kp = page_address(page); unsigned int kp_ofs; ntfs_debug("Zeroing page region outside initialized size."); if (((s64)page->index << PAGE_SHIFT) >= initialized_size) { clear_page(kp); return; } kp_ofs = initialized_size & ~PAGE_MASK; memset(kp + kp_ofs, 0, PAGE_SIZE - kp_ofs); return; } /** * handle_bounds_compressed_page - test for&handle out of bounds compressed page */ static inline void handle_bounds_compressed_page(struct page *page, const loff_t i_size, const s64 initialized_size) { if ((page->index >= (initialized_size >> PAGE_SHIFT)) && (initialized_size < i_size)) zero_partial_compressed_page(page, initialized_size); return; } /** * ntfs_decompress - decompress a compression block into an array of pages * @dest_pages: destination array of pages * @dest_index: current index into @dest_pages (IN/OUT) * @dest_ofs: current offset within @dest_pages[@dest_index] (IN/OUT) * @dest_max_index: maximum index into @dest_pages (IN) * @dest_max_ofs: maximum offset within @dest_pages[@dest_max_index] (IN) * @xpage: the target page (-1 if none) (IN) * @xpage_done: set to 1 if xpage was completed successfully (IN/OUT) * @cb_start: compression block to decompress (IN) * @cb_size: size of compression block @cb_start in bytes (IN) * @i_size: file size when we started the read (IN) * @initialized_size: initialized file size when we started the read (IN) * * The caller must have disabled preemption. ntfs_decompress() reenables it when * the critical section is finished. * * This decompresses the compression block @cb_start into the array of * destination pages @dest_pages starting at index @dest_index into @dest_pages * and at offset @dest_pos into the page @dest_pages[@dest_index]. * * When the page @dest_pages[@xpage] is completed, @xpage_done is set to 1. * If xpage is -1 or @xpage has not been completed, @xpage_done is not modified. * * @cb_start is a pointer to the compression block which needs decompressing * and @cb_size is the size of @cb_start in bytes (8-64kiB). * * Return 0 if success or -EOVERFLOW on error in the compressed stream. * @xpage_done indicates whether the target page (@dest_pages[@xpage]) was * completed during the decompression of the compression block (@cb_start). * * Warning: This function *REQUIRES* PAGE_SIZE >= 4096 or it will blow up * unpredicatbly! You have been warned! * * Note to hackers: This function may not sleep until it has finished accessing * the compression block @cb_start as it is a per-CPU buffer. */ static int ntfs_decompress(struct page *dest_pages[], int *dest_index, int *dest_ofs, const int dest_max_index, const int dest_max_ofs, const int xpage, char *xpage_done, u8 *const cb_start, const u32 cb_size, const loff_t i_size, const s64 initialized_size) { /* * Pointers into the compressed data, i.e. the compression block (cb), * and the therein contained sub-blocks (sb). */ u8 *cb_end = cb_start + cb_size; /* End of cb. */ u8 *cb = cb_start; /* Current position in cb. */ u8 *cb_sb_start = cb; /* Beginning of the current sb in the cb. */ u8 *cb_sb_end; /* End of current sb / beginning of next sb. */ /* Variables for uncompressed data / destination. */ struct page *dp; /* Current destination page being worked on. */ u8 *dp_addr; /* Current pointer into dp. */ u8 *dp_sb_start; /* Start of current sub-block in dp. */ u8 *dp_sb_end; /* End of current sb in dp (dp_sb_start + NTFS_SB_SIZE). */ u16 do_sb_start; /* @dest_ofs when starting this sub-block. */ u16 do_sb_end; /* @dest_ofs of end of this sb (do_sb_start + NTFS_SB_SIZE). */ /* Variables for tag and token parsing. */ u8 tag; /* Current tag. */ int token; /* Loop counter for the eight tokens in tag. */ /* Need this because we can't sleep, so need two stages. */ int completed_pages[dest_max_index - *dest_index + 1]; int nr_completed_pages = 0; /* Default error code. */ int err = -EOVERFLOW; ntfs_debug("Entering, cb_size = 0x%x.", cb_size); do_next_sb: ntfs_debug("Beginning sub-block at offset = 0x%zx in the cb.", cb - cb_start); /* * Have we reached the end of the compression block or the end of the * decompressed data? The latter can happen for example if the current * position in the compression block is one byte before its end so the * first two checks do not detect it. */ if (cb == cb_end || !le16_to_cpup((le16*)cb) || (*dest_index == dest_max_index && *dest_ofs == dest_max_ofs)) { int i; ntfs_debug("Completed. Returning success (0)."); err = 0; return_error: /* We can sleep from now on, so we drop lock. */ spin_unlock(&ntfs_cb_lock); /* Second stage: finalize completed pages. */ if (nr_completed_pages > 0) { for (i = 0; i < nr_completed_pages; i++) { int di = completed_pages[i]; dp = dest_pages[di]; /* * If we are outside the initialized size, zero * the out of bounds page range. */ handle_bounds_compressed_page(dp, i_size, initialized_size); flush_dcache_page(dp); kunmap(dp); SetPageUptodate(dp); unlock_page(dp); if (di == xpage) *xpage_done = 1; else put_page(dp); dest_pages[di] = NULL; } } return err; } /* Setup offsets for the current sub-block destination. */ do_sb_start = *dest_ofs; do_sb_end = do_sb_start + NTFS_SB_SIZE; /* Check that we are still within allowed boundaries. */ if (*dest_index == dest_max_index && do_sb_end > dest_max_ofs) goto return_overflow; /* Does the minimum size of a compressed sb overflow valid range? */ if (cb + 6 > cb_end) goto return_overflow; /* Setup the current sub-block source pointers and validate range. */ cb_sb_start = cb; cb_sb_end = cb_sb_start + (le16_to_cpup((le16*)cb) & NTFS_SB_SIZE_MASK) + 3; if (cb_sb_end > cb_end) goto return_overflow; /* Get the current destination page. */ dp = dest_pages[*dest_index]; if (!dp) { /* No page present. Skip decompression of this sub-block. */ cb = cb_sb_end; /* Advance destination position to next sub-block. */ *dest_ofs = (*dest_ofs + NTFS_SB_SIZE) & ~PAGE_MASK; if (!*dest_ofs && (++*dest_index > dest_max_index)) goto return_overflow; goto do_next_sb; } /* We have a valid destination page. Setup the destination pointers. */ dp_addr = (u8*)page_address(dp) + do_sb_start; /* Now, we are ready to process the current sub-block (sb). */ if (!(le16_to_cpup((le16*)cb) & NTFS_SB_IS_COMPRESSED)) { ntfs_debug("Found uncompressed sub-block."); /* This sb is not compressed, just copy it into destination. */ /* Advance source position to first data byte. */ cb += 2; /* An uncompressed sb must be full size. */ if (cb_sb_end - cb != NTFS_SB_SIZE) goto return_overflow; /* Copy the block and advance the source position. */ memcpy(dp_addr, cb, NTFS_SB_SIZE); cb += NTFS_SB_SIZE; /* Advance destination position to next sub-block. */ *dest_ofs += NTFS_SB_SIZE; if (!(*dest_ofs &= ~PAGE_MASK)) { finalize_page: /* * First stage: add current page index to array of * completed pages. */ completed_pages[nr_completed_pages++] = *dest_index; if (++*dest_index > dest_max_index) goto return_overflow; } goto do_next_sb; } ntfs_debug("Found compressed sub-block."); /* This sb is compressed, decompress it into destination. */ /* Setup destination pointers. */ dp_sb_start = dp_addr; dp_sb_end = dp_sb_start + NTFS_SB_SIZE; /* Forward to the first tag in the sub-block. */ cb += 2; do_next_tag: if (cb == cb_sb_end) { /* Check if the decompressed sub-block was not full-length. */ if (dp_addr < dp_sb_end) { int nr_bytes = do_sb_end - *dest_ofs; ntfs_debug("Filling incomplete sub-block with " "zeroes."); /* Zero remainder and update destination position. */ memset(dp_addr, 0, nr_bytes); *dest_ofs += nr_bytes; } /* We have finished the current sub-block. */ if (!(*dest_ofs &= ~PAGE_MASK)) goto finalize_page; goto do_next_sb; } /* Check we are still in range. */ if (cb > cb_sb_end || dp_addr > dp_sb_end) goto return_overflow; /* Get the next tag and advance to first token. */ tag = *cb++; /* Parse the eight tokens described by the tag. */ for (token = 0; token < 8; token++, tag >>= 1) { u16 lg, pt, length, max_non_overlap; register u16 i; u8 *dp_back_addr; /* Check if we are done / still in range. */ if (cb >= cb_sb_end || dp_addr > dp_sb_end) break; /* Determine token type and parse appropriately.*/ if ((tag & NTFS_TOKEN_MASK) == NTFS_SYMBOL_TOKEN) { /* * We have a symbol token, copy the symbol across, and * advance the source and destination positions. */ *dp_addr++ = *cb++; ++*dest_ofs; /* Continue with the next token. */ continue; } /* * We have a phrase token. Make sure it is not the first tag in * the sb as this is illegal and would confuse the code below. */ if (dp_addr == dp_sb_start) goto return_overflow; /* * Determine the number of bytes to go back (p) and the number * of bytes to copy (l). We use an optimized algorithm in which * we first calculate log2(current destination position in sb), * which allows determination of l and p in O(1) rather than * O(n). We just need an arch-optimized log2() function now. */ lg = 0; for (i = *dest_ofs - do_sb_start - 1; i >= 0x10; i >>= 1) lg++; /* Get the phrase token into i. */ pt = le16_to_cpup((le16*)cb); /* * Calculate starting position of the byte sequence in * the destination using the fact that p = (pt >> (12 - lg)) + 1 * and make sure we don't go too far back. */ dp_back_addr = dp_addr - (pt >> (12 - lg)) - 1; if (dp_back_addr < dp_sb_start) goto return_overflow; /* Now calculate the length of the byte sequence. */ length = (pt & (0xfff >> lg)) + 3; /* Advance destination position and verify it is in range. */ *dest_ofs += length; if (*dest_ofs > do_sb_end) goto return_overflow; /* The number of non-overlapping bytes. */ max_non_overlap = dp_addr - dp_back_addr; if (length <= max_non_overlap) { /* The byte sequence doesn't overlap, just copy it. */ memcpy(dp_addr, dp_back_addr, length); /* Advance destination pointer. */ dp_addr += length; } else { /* * The byte sequence does overlap, copy non-overlapping * part and then do a slow byte by byte copy for the * overlapping part. Also, advance the destination * pointer. */ memcpy(dp_addr, dp_back_addr, max_non_overlap); dp_addr += max_non_overlap; dp_back_addr += max_non_overlap; length -= max_non_overlap; while (length--) *dp_addr++ = *dp_back_addr++; } /* Advance source position and continue with the next token. */ cb += 2; } /* No tokens left in the current tag. Continue with the next tag. */ goto do_next_tag; return_overflow: ntfs_error(NULL, "Failed. Returning -EOVERFLOW."); goto return_error; } /** * ntfs_read_compressed_block - read a compressed block into the page cache * @page: locked page in the compression block(s) we need to read * * When we are called the page has already been verified to be locked and the * attribute is known to be non-resident, not encrypted, but compressed. * * 1. Determine which compression block(s) @page is in. * 2. Get hold of all pages corresponding to this/these compression block(s). * 3. Read the (first) compression block. * 4. Decompress it into the corresponding pages. * 5. Throw the compressed data away and proceed to 3. for the next compression * block or return success if no more compression blocks left. * * Warning: We have to be careful what we do about existing pages. They might * have been written to so that we would lose data if we were to just overwrite * them with the out-of-date uncompressed data. * * FIXME: For PAGE_SIZE > cb_size we are not doing the Right Thing(TM) at * the end of the file I think. We need to detect this case and zero the out * of bounds remainder of the page in question and mark it as handled. At the * moment we would just return -EIO on such a page. This bug will only become * apparent if pages are above 8kiB and the NTFS volume only uses 512 byte * clusters so is probably not going to be seen by anyone. Still this should * be fixed. (AIA) * * FIXME: Again for PAGE_SIZE > cb_size we are screwing up both in * handling sparse and compressed cbs. (AIA) * * 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_SIZE). */ VCN start_vcn = (((s64)index << PAGE_SHIFT) & ~cb_size_mask) >> vol->cluster_size_bits; /* * The first vcn after the last wanted vcn (minimum alignment is again * PAGE_SIZE. */ VCN end_vcn = ((((s64)(index + 1UL) << PAGE_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_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_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); 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(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_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, &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); /* 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); return -EIO; }