zisofs: Implement reading of compressed files when PAGE_CACHE_SIZE > compress block size

Also split and cleanup zisofs_readpage() when we are changing it anyway.

Signed-off-by: Jan Kara <jack@suse.cz>

1 files changed, 285 insertions, 248 deletions

diff --git a/fs/isofs/compress.c b/fs/isofs/compress.c
index defb932eee9a..0b3fa7974fa8 100644
--- a/fs/isofs/compress.c
+++ b/fs/isofs/compress.c
@@ -36,286 +36,323 @@ static void *zisofs_zlib_workspace;
 static DEFINE_MUTEX(zisofs_zlib_lock);
 
 /*
- * When decompressing, we typically obtain more than one page
- * per reference.  We inject the additional pages into the page
- * cache as a form of readahead.
+ * Read data of @inode from @block_start to @block_end and uncompress
+ * to one zisofs block. Store the data in the @pages array with @pcount
+ * entries. Start storing at offset @poffset of the first page.
  */
-static int zisofs_readpage(struct file *file, struct page *page)
+static loff_t zisofs_uncompress_block(struct inode *inode, loff_t block_start,
+                                      loff_t block_end, int pcount,
+                                      struct page **pages, unsigned poffset,
+                                      int *errp)
 {
-        struct inode *inode = file->f_path.dentry->d_inode;
-        struct address_space *mapping = inode->i_mapping;
-        unsigned int maxpage, xpage, fpage, blockindex;
-        unsigned long offset;
-        unsigned long blockptr, blockendptr, cstart, cend, csize;
-        struct buffer_head *bh, *ptrbh[2];
-        unsigned long bufsize = ISOFS_BUFFER_SIZE(inode);
-        unsigned int bufshift = ISOFS_BUFFER_BITS(inode);
-        unsigned long bufmask  = bufsize - 1;
-        int err = -EIO;
-        int i;
-        unsigned int header_size = ISOFS_I(inode)->i_format_parm[0];
         unsigned int zisofs_block_shift = ISOFS_I(inode)->i_format_parm[1];
-        /* unsigned long zisofs_block_size = 1UL << zisofs_block_shift; */
-        unsigned int zisofs_block_page_shift = zisofs_block_shift-PAGE_CACHE_SHIFT;
-        unsigned long zisofs_block_pages = 1UL << zisofs_block_page_shift;
-        unsigned long zisofs_block_page_mask = zisofs_block_pages-1;
-        struct page *pages[zisofs_block_pages];
-        unsigned long index = page->index;
-        int indexblocks;
-
-        /* We have already been given one page, this is the one
-           we must do. */
-        xpage = index & zisofs_block_page_mask;
-        pages[xpage] = page;
- 
-        /* The remaining pages need to be allocated and inserted */
-        offset = index & ~zisofs_block_page_mask;
-        blockindex = offset >> zisofs_block_page_shift;
-        maxpage = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
-
-        /*
-         * If this page is wholly outside i_size we just return zero;
-         * do_generic_file_read() will handle this for us
-         */
-        if (page->index >= maxpage) {
-                SetPageUptodate(page);
-                unlock_page(page);
+        unsigned int bufsize = ISOFS_BUFFER_SIZE(inode);
+        unsigned int bufshift = ISOFS_BUFFER_BITS(inode);
+        unsigned int bufmask = bufsize - 1;
+        int i, block_size = block_end - block_start;
+        z_stream stream = { .total_out = 0,
+                            .avail_in = 0,
+                            .avail_out = 0, };
+        int zerr;
+        int needblocks = (block_size + (block_start & bufmask) + bufmask)
+                                >> bufshift;
+        int haveblocks;
+        blkcnt_t blocknum;
+        struct buffer_head *bhs[needblocks + 1];
+        int curbh, curpage;
+
+        if (block_size > deflateBound(1UL << zisofs_block_shift)) {
+                *errp = -EIO;
                 return 0;
         }
-
-        maxpage = min(zisofs_block_pages, maxpage-offset);
-
-        for ( i = 0 ; i < maxpage ; i++, offset++ ) {
-                if ( i != xpage ) {
-                        pages[i] = grab_cache_page_nowait(mapping, offset);
-                }
-                page = pages[i];
-                if ( page ) {
-                        ClearPageError(page);
-                        kmap(page);
+        /* Empty block? */
+        if (block_size == 0) {
+                for ( i = 0 ; i < pcount ; i++ ) {
+                        if (!pages[i])
+                                continue;
+                        memset(page_address(pages[i]), 0, PAGE_CACHE_SIZE);
+                        flush_dcache_page(pages[i]);
+                        SetPageUptodate(pages[i]);
                 }
+                return ((loff_t)pcount) << PAGE_CACHE_SHIFT;
         }
 
-        /* This is the last page filled, plus one; used in case of abort. */
-        fpage = 0;
+        /* Because zlib is not thread-safe, do all the I/O at the top. */
+        blocknum = block_start >> bufshift;
+        memset(bhs, 0, (needblocks + 1) * sizeof(struct buffer_head *));
+        haveblocks = isofs_get_blocks(inode, blocknum, bhs, needblocks);
+        ll_rw_block(READ, haveblocks, bhs);
 
-        /* Find the pointer to this specific chunk */
-        /* Note: we're not using isonum_731() here because the data is known aligned */
-        /* Note: header_size is in 32-bit words (4 bytes) */
-        blockptr = (header_size + blockindex) << 2;
-        blockendptr = blockptr + 4;
+        curbh = 0;
+        curpage = 0;
+        /*
+         * First block is special since it may be fractional.  We also wait for
+         * it before grabbing the zlib mutex; odds are that the subsequent
+         * blocks are going to come in in short order so we don't hold the zlib
+         * mutex longer than necessary.
+         */
 
-        indexblocks = ((blockptr^blockendptr) >> bufshift) ? 2 : 1;
-        ptrbh[0] = ptrbh[1] = NULL;
+        if (!bhs[0])
+                goto b_eio;
 
-        if ( isofs_get_blocks(inode, blockptr >> bufshift, ptrbh, indexblocks) != indexblocks ) {
-                if ( ptrbh[0] ) brelse(ptrbh[0]);
-                printk(KERN_DEBUG "zisofs: Null buffer on reading block table, inode = %lu, block = %lu\n",
-                       inode->i_ino, blockptr >> bufshift);
-                goto eio;
-        }
-        ll_rw_block(READ, indexblocks, ptrbh);
-
-        bh = ptrbh[0];
-        if ( !bh || (wait_on_buffer(bh), !buffer_uptodate(bh)) ) {
-                printk(KERN_DEBUG "zisofs: Failed to read block table, inode = %lu, block = %lu\n",
-                       inode->i_ino, blockptr >> bufshift);
-                if ( ptrbh[1] )
-                        brelse(ptrbh[1]);
-                goto eio;
-        }
-        cstart = le32_to_cpu(*(__le32 *)(bh->b_data + (blockptr & bufmask)));
-
-        if ( indexblocks == 2 ) {
-                /* We just crossed a block boundary.  Switch to the next block */
-                brelse(bh);
-                bh = ptrbh[1];
-                if ( !bh || (wait_on_buffer(bh), !buffer_uptodate(bh)) ) {
-                        printk(KERN_DEBUG "zisofs: Failed to read block table, inode = %lu, block = %lu\n",
-                               inode->i_ino, blockendptr >> bufshift);
-                        goto eio;
-                }
+        wait_on_buffer(bhs[0]);
+        if (!buffer_uptodate(bhs[0])) {
+                *errp = -EIO;
+                goto b_eio;
         }
-        cend = le32_to_cpu(*(__le32 *)(bh->b_data + (blockendptr & bufmask)));
-        brelse(bh);
 
-        if (cstart > cend)
-                goto eio;
+        stream.workspace = zisofs_zlib_workspace;
+        mutex_lock(&zisofs_zlib_lock);
                 
-        csize = cend-cstart;
-
-        if (csize > deflateBound(1UL << zisofs_block_shift))
-                goto eio;
-
-        /* Now page[] contains an array of pages, any of which can be NULL,
-           and the locks on which we hold.  We should now read the data and
-           release the pages.  If the pages are NULL the decompressed data
-           for that particular page should be discarded. */
-        
-        if ( csize == 0 ) {
-                /* This data block is empty. */
-
-                for ( fpage = 0 ; fpage < maxpage ; fpage++ ) {
-                        if ( (page = pages[fpage]) != NULL ) {
-                                memset(page_address(page), 0, PAGE_CACHE_SIZE);
-                                
-                                flush_dcache_page(page);
-                                SetPageUptodate(page);
-                                kunmap(page);
-                                unlock_page(page);
-                                if ( fpage == xpage )
-                                        err = 0; /* The critical page */
-                                else
-                                        page_cache_release(page);
+        zerr = zlib_inflateInit(&stream);
+        if (zerr != Z_OK) {
+                if (zerr == Z_MEM_ERROR)
+                        *errp = -ENOMEM;
+                else
+                        *errp = -EIO;
+                printk(KERN_DEBUG "zisofs: zisofs_inflateInit returned %d\n",
+                               zerr);
+                goto z_eio;
+        }
+
+        while (curpage < pcount && curbh < haveblocks &&
+               zerr != Z_STREAM_END) {
+                if (!stream.avail_out) {
+                        if (pages[curpage]) {
+                                stream.next_out = page_address(pages[curpage])
+                                                + poffset;
+                                stream.avail_out = PAGE_CACHE_SIZE - poffset;
+                                poffset = 0;
+                        } else {
+                                stream.next_out = (void *)&zisofs_sink_page;
+                                stream.avail_out = PAGE_CACHE_SIZE;
                         }
                 }
-        } else {
-                /* This data block is compressed. */
-                z_stream stream;
-                int bail = 0, left_out = -1;
-                int zerr;
-                int needblocks = (csize + (cstart & bufmask) + bufmask) >> bufshift;
-                int haveblocks;
-                struct buffer_head *bhs[needblocks+1];
-                struct buffer_head **bhptr;
-
-                /* Because zlib is not thread-safe, do all the I/O at the top. */
-
-                blockptr = cstart >> bufshift;
-                memset(bhs, 0, (needblocks+1)*sizeof(struct buffer_head *));
-                haveblocks = isofs_get_blocks(inode, blockptr, bhs, needblocks);
-                ll_rw_block(READ, haveblocks, bhs);
-
-                bhptr = &bhs[0];
-                bh = *bhptr++;
-
-                /* First block is special since it may be fractional.
-                   We also wait for it before grabbing the zlib
-                   mutex; odds are that the subsequent blocks are
-                   going to come in in short order so we don't hold
-                   the zlib mutex longer than necessary. */
-
-                if ( !bh || (wait_on_buffer(bh), !buffer_uptodate(bh)) ) {
-                        printk(KERN_DEBUG "zisofs: Hit null buffer, fpage = %d, xpage = %d, csize = %ld\n",
-                               fpage, xpage, csize);
-                        goto b_eio;
-                }
-                stream.next_in  = bh->b_data + (cstart & bufmask);
-                stream.avail_in = min(bufsize-(cstart & bufmask), csize);
-                csize -= stream.avail_in;
-
-                stream.workspace = zisofs_zlib_workspace;
-                mutex_lock(&zisofs_zlib_lock);
-                
-                zerr = zlib_inflateInit(&stream);
-                if ( zerr != Z_OK ) {
-                        if ( err && zerr == Z_MEM_ERROR )
-                                err = -ENOMEM;
-                        printk(KERN_DEBUG "zisofs: zisofs_inflateInit returned %d\n",
-                               zerr);
-                        goto z_eio;
+                if (!stream.avail_in) {
+                        wait_on_buffer(bhs[curbh]);
+                        if (!buffer_uptodate(bhs[curbh])) {
+                                *errp = -EIO;
+                                break;
+                        }
+                        stream.next_in  = bhs[curbh]->b_data +
+                                                (block_start & bufmask);
+                        stream.avail_in = min_t(unsigned, bufsize -
+                                                (block_start & bufmask),
+                                                block_size);
+                        block_size -= stream.avail_in;
+                        block_start = 0;
                 }
 
-                while ( !bail && fpage < maxpage ) {
-                        page = pages[fpage];
-                        if ( page )
-                                stream.next_out = page_address(page);
-                        else
-                                stream.next_out = (void *)&zisofs_sink_page;
-                        stream.avail_out = PAGE_CACHE_SIZE;
-
-                        while ( stream.avail_out ) {
-                                int ao, ai;
-                                if ( stream.avail_in == 0 && left_out ) {
-                                        if ( !csize ) {
-                                                printk(KERN_WARNING "zisofs: ZF read beyond end of input\n");
-                                                bail = 1;
-                                                break;
-                                        } else {
-                                                bh = *bhptr++;
-                                                if ( !bh ||
-                                                     (wait_on_buffer(bh), !buffer_uptodate(bh)) ) {
-                                                        /* Reached an EIO */
-                                                        printk(KERN_DEBUG "zisofs: Hit null buffer, fpage = %d, xpage = %d, csize = %ld\n",
-                                                               fpage, xpage, csize);
-                                                               
-                                                        bail = 1;
-                                                        break;
-                                                }
-                                                stream.next_in = bh->b_data;
-                                                stream.avail_in = min(csize,bufsize);
-                                                csize -= stream.avail_in;
-                                        }
-                                }
-                                ao = stream.avail_out;  ai = stream.avail_in;
-                                zerr = zlib_inflate(&stream, Z_SYNC_FLUSH);
-                                left_out = stream.avail_out;
-                                if ( zerr == Z_BUF_ERROR && stream.avail_in == 0 )
-                                        continue;
-                                if ( zerr != Z_OK ) {
-                                        /* EOF, error, or trying to read beyond end of input */
-                                        if ( err && zerr == Z_MEM_ERROR )
-                                                err = -ENOMEM;
-                                        if ( zerr != Z_STREAM_END )
-                                                printk(KERN_DEBUG "zisofs: zisofs_inflate returned %d, inode = %lu, index = %lu, fpage = %d, xpage = %d, avail_in = %d, avail_out = %d, ai = %d, ao = %d\n",
-                                                       zerr, inode->i_ino, index,
-                                                       fpage, xpage,
-                                                       stream.avail_in, stream.avail_out,
-                                                       ai, ao);
-                                        bail = 1;
-                                        break;
+                while (stream.avail_out && stream.avail_in) {
+                        zerr = zlib_inflate(&stream, Z_SYNC_FLUSH);
+                        if (zerr == Z_BUF_ERROR && stream.avail_in == 0)
+                                break;
+                        if (zerr == Z_STREAM_END)
+                                break;
+                        if (zerr != Z_OK) {
+                                /* EOF, error, or trying to read beyond end of input */
+                                if (zerr == Z_MEM_ERROR)
+                                        *errp = -ENOMEM;
+                                else {
+                                        printk(KERN_DEBUG
+                                               "zisofs: zisofs_inflate returned"
+                                               " %d, inode = %lu,"
+                                               " page idx = %d, bh idx = %d,"
+                                               " avail_in = %d,"
+                                               " avail_out = %d\n",
+                                               zerr, inode->i_ino, curpage,
+                                               curbh, stream.avail_in,
+                                               stream.avail_out);
+                                        *errp = -EIO;
                                 }
+                                goto inflate_out;
                         }
+                }
 
-                        if ( stream.avail_out && zerr == Z_STREAM_END ) {
-                                /* Fractional page written before EOF.  This may
-                                   be the last page in the file. */
-                                memset(stream.next_out, 0, stream.avail_out);
-                                stream.avail_out = 0;
+                if (!stream.avail_out) {
+                        /* This page completed */
+                        if (pages[curpage]) {
+                                flush_dcache_page(pages[curpage]);
+                                SetPageUptodate(pages[curpage]);
                         }
+                        curpage++;
+                }
+                if (!stream.avail_in)
+                        curbh++;
+        }
+inflate_out:
+        zlib_inflateEnd(&stream);
 
-                        if ( !stream.avail_out ) {
-                                /* This page completed */
-                                if ( page ) {
-                                        flush_dcache_page(page);
-                                        SetPageUptodate(page);
-                                        kunmap(page);
-                                        unlock_page(page);
-                                        if ( fpage == xpage )
-                                                err = 0; /* The critical page */
-                                        else
-                                                page_cache_release(page);
-                                }
-                                fpage++;
-                        }
+z_eio:
+        mutex_unlock(&zisofs_zlib_lock);
+
+b_eio:
+        for (i = 0; i < haveblocks; i++)
+                brelse(bhs[i]);
+        return stream.total_out;
+}
+
+/*
+ * Uncompress data so that pages[full_page] is fully uptodate and possibly
+ * fills in other pages if we have data for them.
+ */
+static int zisofs_fill_pages(struct inode *inode, int full_page, int pcount,
+                             struct page **pages)
+{
+        loff_t start_off, end_off;
+        loff_t block_start, block_end;
+        unsigned int header_size = ISOFS_I(inode)->i_format_parm[0];
+        unsigned int zisofs_block_shift = ISOFS_I(inode)->i_format_parm[1];
+        unsigned int blockptr;
+        loff_t poffset = 0;
+        blkcnt_t cstart_block, cend_block;
+        struct buffer_head *bh;
+        unsigned int blkbits = ISOFS_BUFFER_BITS(inode);
+        unsigned int blksize = 1 << blkbits;
+        int err;
+        loff_t ret;
+
+        BUG_ON(!pages[full_page]);
+
+        /*
+         * We want to read at least 'full_page' page. Because we have to
+         * uncompress the whole compression block anyway, fill the surrounding
+         * pages with the data we have anyway...
+         */
+        start_off = page_offset(pages[full_page]);
+        end_off = min_t(loff_t, start_off + PAGE_CACHE_SIZE, inode->i_size);
+
+        cstart_block = start_off >> zisofs_block_shift;
+        cend_block = (end_off + (1 << zisofs_block_shift) - 1)
+                        >> zisofs_block_shift;
+
+        WARN_ON(start_off - (full_page << PAGE_CACHE_SHIFT) !=
+                ((cstart_block << zisofs_block_shift) & PAGE_CACHE_MASK));
+
+        /* Find the pointer to this specific chunk */
+        /* Note: we're not using isonum_731() here because the data is known aligned */
+        /* Note: header_size is in 32-bit words (4 bytes) */
+        blockptr = (header_size + cstart_block) << 2;
+        bh = isofs_bread(inode, blockptr >> blkbits);
+        if (!bh)
+                return -EIO;
+        block_start = le32_to_cpu(*(__le32 *)
+                                (bh->b_data + (blockptr & (blksize - 1))));
+
+        while (cstart_block < cend_block && pcount > 0) {
+                /* Load end of the compressed block in the file */
+                blockptr += 4;
+                /* Traversed to next block? */
+                if (!(blockptr & (blksize - 1))) {
+                        brelse(bh);
+
+                        bh = isofs_bread(inode, blockptr >> blkbits);
+                        if (!bh)
+                                return -EIO;
+                }
+                block_end = le32_to_cpu(*(__le32 *)
+                                (bh->b_data + (blockptr & (blksize - 1))));
+                if (block_start > block_end) {
+                        brelse(bh);
+                        return -EIO;
+                }
+                err = 0;
+                ret = zisofs_uncompress_block(inode, block_start, block_end,
+                                              pcount, pages, poffset, &err);
+                poffset += ret;
+                pages += poffset >> PAGE_CACHE_SHIFT;
+                pcount -= poffset >> PAGE_CACHE_SHIFT;
+                full_page -= poffset >> PAGE_CACHE_SHIFT;
+                poffset &= ~PAGE_CACHE_MASK;
+
+                if (err) {
+                        brelse(bh);
+                        /*
+                         * Did we finish reading the page we really wanted
+                         * to read?
+                         */
+                        if (full_page < 0)
+                                return 0;
+                        return err;
                 }
-                zlib_inflateEnd(&stream);
 
-        z_eio:
-                mutex_unlock(&zisofs_zlib_lock);
+                block_start = block_end;
+                cstart_block++;
+        }
+
+        if (poffset && *pages) {
+                memset(page_address(*pages) + poffset, 0,
+                       PAGE_CACHE_SIZE - poffset);
+                flush_dcache_page(*pages);
+                SetPageUptodate(*pages);
+        }
+        return 0;
+}
 
-        b_eio:
-                for ( i = 0 ; i < haveblocks ; i++ ) {
-                        if ( bhs[i] )
-                                brelse(bhs[i]);
+/*
+ * When decompressing, we typically obtain more than one page
+ * per reference.  We inject the additional pages into the page
+ * cache as a form of readahead.
+ */
+static int zisofs_readpage(struct file *file, struct page *page)
+{
+        struct inode *inode = file->f_path.dentry->d_inode;
+        struct address_space *mapping = inode->i_mapping;
+        int err;
+        int i, pcount, full_page;
+        unsigned int zisofs_block_shift = ISOFS_I(inode)->i_format_parm[1];
+        unsigned int zisofs_pages_per_cblock =
+                PAGE_CACHE_SHIFT <= zisofs_block_shift ?
+                (1 << (zisofs_block_shift - PAGE_CACHE_SHIFT)) : 0;
+        struct page *pages[max_t(unsigned, zisofs_pages_per_cblock, 1)];
+        pgoff_t index = page->index, end_index;
+
+        end_index = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+        /*
+         * If this page is wholly outside i_size we just return zero;
+         * do_generic_file_read() will handle this for us
+         */
+        if (index >= end_index) {
+                SetPageUptodate(page);
+                unlock_page(page);
+                return 0;
+        }
+
+        if (PAGE_CACHE_SHIFT <= zisofs_block_shift) {
+                /* We have already been given one page, this is the one
+                   we must do. */
+                full_page = index & (zisofs_pages_per_cblock - 1);
+                pcount = min_t(int, zisofs_pages_per_cblock,
+                        end_index - (index & ~(zisofs_pages_per_cblock - 1)));
+                index -= full_page;
+        } else {
+                full_page = 0;
+                pcount = 1;
+        }
+        pages[full_page] = page;
+
+        for (i = 0; i < pcount; i++, index++) {
+                if (i != full_page)
+                        pages[i] = grab_cache_page_nowait(mapping, index);
+                if (pages[i]) {
+                        ClearPageError(pages[i]);
+                        kmap(pages[i]);
                 }
         }
 
-eio:
+        err = zisofs_fill_pages(inode, full_page, pcount, pages);
 
         /* Release any residual pages, do not SetPageUptodate */
-        while ( fpage < maxpage ) {
-                page = pages[fpage];
-                if ( page ) {
-                        flush_dcache_page(page);
-                        if ( fpage == xpage )
-                                SetPageError(page);
-                        kunmap(page);
-                        unlock_page(page);
-                        if ( fpage != xpage )
-                                page_cache_release(page);
+        for (i = 0; i < pcount; i++) {
+                if (pages[i]) {
+                        flush_dcache_page(pages[i]);
+                        if (i == full_page && err)
+                                SetPageError(pages[i]);
+                        kunmap(pages[i]);
+                        unlock_page(pages[i]);
+                        if (i != full_page)
+                                page_cache_release(pages[i]);
                 }
-                fpage++;
         }                       
 
         /* At this point, err contains 0 or -EIO depending on the "critical" page */