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Diffstat (limited to 'fs/ntfs/compress.c')
| -rw-r--r-- | fs/ntfs/compress.c | 957 |
1 files changed, 957 insertions, 0 deletions
diff --git a/fs/ntfs/compress.c b/fs/ntfs/compress.c new file mode 100644 index 0000000..ee5ae70 --- /dev/null +++ b/fs/ntfs/compress.c @@ -0,0 +1,957 @@ +/** + * 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 "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 = NULL; + +/** + * 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 semaphore. + * + * 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 semaphore. + */ +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(ntfs_inode *ni, struct page *page) +{ + u8 *kp = page_address(page); + unsigned int kp_ofs; + + ntfs_debug("Zeroing page region outside initialized size."); + if (((s64)page->index << PAGE_CACHE_SHIFT) >= ni->initialized_size) { + /* + * FIXME: Using clear_page() will become wrong when we get + * PAGE_CACHE_SIZE != PAGE_SIZE but for now there is no problem. + */ + clear_page(kp); + return; + } + kp_ofs = ni->initialized_size & ~PAGE_CACHE_MASK; + memset(kp + kp_ofs, 0, PAGE_CACHE_SIZE - kp_ofs); + return; +} + +/** + * handle_bounds_compressed_page - test for&handle out of bounds compressed page + */ +static inline void handle_bounds_compressed_page(ntfs_inode *ni, + struct page *page) +{ + if ((page->index >= (ni->initialized_size >> PAGE_CACHE_SHIFT)) && + (ni->initialized_size < VFS_I(ni)->i_size)) + zero_partial_compressed_page(ni, page); + 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) + * + * 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_CACHE_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) +{ + /* + * 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) { + struct page *page = dest_pages[completed_pages[0]]; + ntfs_inode *ni = NTFS_I(page->mapping->host); + + 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(ni, dp); + flush_dcache_page(dp); + kunmap(dp); + SetPageUptodate(dp); + unlock_page(dp); + if (di == xpage) + *xpage_done = 1; + else + page_cache_release(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_CACHE_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_CACHE_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_CACHE_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_CACHE_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_CACHE_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) +{ + 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 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 (minumum 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); + SetPageError(page); + 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 + */ + max_page = ((VFS_I(ni)->i_size + PAGE_CACHE_SIZE - 1) >> + PAGE_CACHE_SHIFT) - offset; + 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 (unlikely(test_set_buffer_locked(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); + blk_run_address_space(mapping); + 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(ni, page); + 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)); + /* + * 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) { + if (prev_cur_page == xpage && + !xpage_done) + SetPageError(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); + if (cur_page == xpage && !xpage_done) + SetPageError(page); + 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" : "unkown 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) { + if (i == xpage && !xpage_done) + SetPageError(page); + flush_dcache_page(page); + kunmap(page); + unlock_page(page); + if (i != xpage) + page_cache_release(page); + } + } + kfree(pages); + return -EIO; +} |
