diff options
Diffstat (limited to 'fs/ubifs/file.c')
-rw-r--r-- | fs/ubifs/file.c | 248 |
1 files changed, 248 insertions, 0 deletions
diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c index 3d698e2022b..cdcfe95cbfb 100644 --- a/fs/ubifs/file.c +++ b/fs/ubifs/file.c @@ -577,8 +577,256 @@ out: return copied; } +/** + * populate_page - copy data nodes into a page for bulk-read. + * @c: UBIFS file-system description object + * @page: page + * @bu: bulk-read information + * @n: next zbranch slot + * + * This function returns %0 on success and a negative error code on failure. + */ +static int populate_page(struct ubifs_info *c, struct page *page, + struct bu_info *bu, int *n) +{ + int i = 0, nn = *n, offs = bu->zbranch[0].offs, hole = 1, read = 0; + struct inode *inode = page->mapping->host; + loff_t i_size = i_size_read(inode); + unsigned int page_block; + void *addr, *zaddr; + pgoff_t end_index; + + dbg_gen("ino %lu, pg %lu, i_size %lld, flags %#lx", + inode->i_ino, page->index, i_size, page->flags); + + addr = zaddr = kmap(page); + + end_index = (i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; + if (!i_size || page->index > end_index) { + memset(addr, 0, PAGE_CACHE_SIZE); + goto out_hole; + } + + page_block = page->index << UBIFS_BLOCKS_PER_PAGE_SHIFT; + while (1) { + int err, len, out_len, dlen; + + if (nn >= bu->cnt || + key_block(c, &bu->zbranch[nn].key) != page_block) + memset(addr, 0, UBIFS_BLOCK_SIZE); + else { + struct ubifs_data_node *dn; + + dn = bu->buf + (bu->zbranch[nn].offs - offs); + + ubifs_assert(dn->ch.sqnum > + ubifs_inode(inode)->creat_sqnum); + + len = le32_to_cpu(dn->size); + if (len <= 0 || len > UBIFS_BLOCK_SIZE) + goto out_err; + + dlen = le32_to_cpu(dn->ch.len) - UBIFS_DATA_NODE_SZ; + out_len = UBIFS_BLOCK_SIZE; + err = ubifs_decompress(&dn->data, dlen, addr, &out_len, + le16_to_cpu(dn->compr_type)); + if (err || len != out_len) + goto out_err; + + if (len < UBIFS_BLOCK_SIZE) + memset(addr + len, 0, UBIFS_BLOCK_SIZE - len); + + nn += 1; + hole = 0; + read = (i << UBIFS_BLOCK_SHIFT) + len; + } + if (++i >= UBIFS_BLOCKS_PER_PAGE) + break; + addr += UBIFS_BLOCK_SIZE; + page_block += 1; + } + + if (end_index == page->index) { + int len = i_size & (PAGE_CACHE_SIZE - 1); + + if (len < read) + memset(zaddr + len, 0, read - len); + } + +out_hole: + if (hole) { + SetPageChecked(page); + dbg_gen("hole"); + } + + SetPageUptodate(page); + ClearPageError(page); + flush_dcache_page(page); + kunmap(page); + *n = nn; + return 0; + +out_err: + ClearPageUptodate(page); + SetPageError(page); + flush_dcache_page(page); + kunmap(page); + ubifs_err("bad data node (block %u, inode %lu)", + page_block, inode->i_ino); + return -EINVAL; +} + +/** + * ubifs_do_bulk_read - do bulk-read. + * @c: UBIFS file-system description object + * @page1: first page + * + * This function returns %1 if the bulk-read is done, otherwise %0 is returned. + */ +static int ubifs_do_bulk_read(struct ubifs_info *c, struct page *page1) +{ + pgoff_t offset = page1->index, end_index; + struct address_space *mapping = page1->mapping; + struct inode *inode = mapping->host; + struct ubifs_inode *ui = ubifs_inode(inode); + struct bu_info *bu; + int err, page_idx, page_cnt, ret = 0, n = 0; + loff_t isize; + + bu = kmalloc(sizeof(struct bu_info), GFP_NOFS); + if (!bu) + return 0; + + bu->buf_len = c->bulk_read_buf_size; + bu->buf = kmalloc(bu->buf_len, GFP_NOFS); + if (!bu->buf) + goto out_free; + + data_key_init(c, &bu->key, inode->i_ino, + offset << UBIFS_BLOCKS_PER_PAGE_SHIFT); + + err = ubifs_tnc_get_bu_keys(c, bu); + if (err) + goto out_warn; + + if (bu->eof) { + /* Turn off bulk-read at the end of the file */ + ui->read_in_a_row = 1; + ui->bulk_read = 0; + } + + page_cnt = bu->blk_cnt >> UBIFS_BLOCKS_PER_PAGE_SHIFT; + if (!page_cnt) { + /* + * This happens when there are multiple blocks per page and the + * blocks for the first page we are looking for, are not + * together. If all the pages were like this, bulk-read would + * reduce performance, so we turn it off for a while. + */ + ui->read_in_a_row = 0; + ui->bulk_read = 0; + goto out_free; + } + + if (bu->cnt) { + err = ubifs_tnc_bulk_read(c, bu); + if (err) + goto out_warn; + } + + err = populate_page(c, page1, bu, &n); + if (err) + goto out_warn; + + unlock_page(page1); + ret = 1; + + isize = i_size_read(inode); + if (isize == 0) + goto out_free; + end_index = ((isize - 1) >> PAGE_CACHE_SHIFT); + + for (page_idx = 1; page_idx < page_cnt; page_idx++) { + pgoff_t page_offset = offset + page_idx; + struct page *page; + + if (page_offset > end_index) + break; + page = find_or_create_page(mapping, page_offset, + GFP_NOFS | __GFP_COLD); + if (!page) + break; + if (!PageUptodate(page)) + err = populate_page(c, page, bu, &n); + unlock_page(page); + page_cache_release(page); + if (err) + break; + } + + ui->last_page_read = offset + page_idx - 1; + +out_free: + kfree(bu->buf); + kfree(bu); + return ret; + +out_warn: + ubifs_warn("ignoring error %d and skipping bulk-read", err); + goto out_free; +} + +/** + * ubifs_bulk_read - determine whether to bulk-read and, if so, do it. + * @page: page from which to start bulk-read. + * + * Some flash media are capable of reading sequentially at faster rates. UBIFS + * bulk-read facility is designed to take advantage of that, by reading in one + * go consecutive data nodes that are also located consecutively in the same + * LEB. This function returns %1 if a bulk-read is done and %0 otherwise. + */ +static int ubifs_bulk_read(struct page *page) +{ + struct inode *inode = page->mapping->host; + struct ubifs_info *c = inode->i_sb->s_fs_info; + struct ubifs_inode *ui = ubifs_inode(inode); + pgoff_t index = page->index, last_page_read = ui->last_page_read; + int ret = 0; + + ui->last_page_read = index; + + if (!c->bulk_read) + return 0; + /* + * Bulk-read is protected by ui_mutex, but it is an optimization, so + * don't bother if we cannot lock the mutex. + */ + if (!mutex_trylock(&ui->ui_mutex)) + return 0; + if (index != last_page_read + 1) { + /* Turn off bulk-read if we stop reading sequentially */ + ui->read_in_a_row = 1; + if (ui->bulk_read) + ui->bulk_read = 0; + goto out_unlock; + } + if (!ui->bulk_read) { + ui->read_in_a_row += 1; + if (ui->read_in_a_row < 3) + goto out_unlock; + /* Three reads in a row, so switch on bulk-read */ + ui->bulk_read = 1; + } + ret = ubifs_do_bulk_read(c, page); +out_unlock: + mutex_unlock(&ui->ui_mutex); + return ret; +} + static int ubifs_readpage(struct file *file, struct page *page) { + if (ubifs_bulk_read(page)) + return 0; do_readpage(page); unlock_page(page); return 0; |