Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
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;
+}