/** * aops.c - NTFS kernel address space operations and page cache handling. * Part of the Linux-NTFS project. * * Copyright (c) 2001-2007 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 #include #include #include #include #include #include #include #include #include "aops.h" #include "attrib.h" #include "debug.h" #include "inode.h" #include "mft.h" #include "runlist.h" #include "types.h" #include "ntfs.h" /** * ntfs_end_buffer_async_read - async io completion for reading attributes * @bh: buffer head on which io is completed * @uptodate: whether @bh is now uptodate or not * * Asynchronous I/O completion handler for reading pages belonging to the * attribute address space of an inode. The inodes can either be files or * directories or they can be fake inodes describing some attribute. * * If NInoMstProtected(), perform the post read mst fixups when all IO on the * page has been completed and mark the page uptodate or set the error bit on * the page. To determine the size of the records that need fixing up, we * cheat a little bit by setting the index_block_size in ntfs_inode to the ntfs * record size, and index_block_size_bits, to the log(base 2) of the ntfs * record size. */ static void ntfs_end_buffer_async_read(struct buffer_head *bh, int uptodate) { unsigned long flags; struct buffer_head *first, *tmp; struct page *page; struct inode *vi; ntfs_inode *ni; int page_uptodate = 1; page = bh->b_page; vi = page->mapping->host; ni = NTFS_I(vi); if (likely(uptodate)) { loff_t i_size; s64 file_ofs, init_size; set_buffer_uptodate(bh); file_ofs = ((s64)page->index << PAGE_CACHE_SHIFT) + bh_offset(bh); read_lock_irqsave(&ni->size_lock, flags); init_size = ni->initialized_size; i_size = i_size_read(vi); read_unlock_irqrestore(&ni->size_lock, flags); if (unlikely(init_size > i_size)) { /* Race with shrinking truncate. */ init_size = i_size; } /* Check for the current buffer head overflowing. */ if (unlikely(file_ofs + bh->b_size > init_size)) { int ofs; void *kaddr; ofs = 0; if (file_ofs < init_size) ofs = init_size - file_ofs; local_irq_save(flags); kaddr = kmap_atomic(page, KM_BIO_SRC_IRQ); memset(kaddr + bh_offset(bh) + ofs, 0, bh->b_size - ofs); flush_dcache_page(page); kunmap_atomic(kaddr, KM_BIO_SRC_IRQ); local_irq_restore(flags); } } else { clear_buffer_uptodate(bh); SetPageError(page); ntfs_error(ni->vol->sb, "Buffer I/O error, logical block " "0x%llx.", (unsigned long long)bh->b_blocknr); } first = page_buffers(page); local_irq_save(flags); bit_spin_lock(BH_Uptodate_Lock, &first->b_state); clear_buffer_async_read(bh); unlock_buffer(bh); tmp = bh; do { if (!buffer_uptodate(tmp)) page_uptodate = 0; if (buffer_async_read(tmp)) { if (likely(buffer_locked(tmp))) goto still_busy; /* Async buffers must be locked. */ BUG(); } tmp = tmp->b_this_page; } while (tmp != bh); bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); local_irq_restore(flags); /* * If none of the buffers had errors then we can set the page uptodate, * but we first have to perform the post read mst fixups, if the * attribute is mst protected, i.e. if NInoMstProteced(ni) is true. * Note we ignore fixup errors as those are detected when * map_mft_record() is called which gives us per record granularity * rather than per page granularity. */ if (!NInoMstProtected(ni)) { if (likely(page_uptodate && !PageError(page))) SetPageUptodate(page); } else { u8 *kaddr; unsigned int i, recs; u32 rec_size; rec_size = ni->itype.index.block_size; recs = PAGE_CACHE_SIZE / rec_size; /* Should have been verified before we got here... */ BUG_ON(!recs); local_irq_save(flags); kaddr = kmap_atomic(page, KM_BIO_SRC_IRQ); for (i = 0; i < recs; i++) post_read_mst_fixup((NTFS_RECORD*)(kaddr + i * rec_size), rec_size); kunmap_atomic(kaddr, KM_BIO_SRC_IRQ); local_irq_restore(flags); flush_dcache_page(page); if (likely(page_uptodate && !PageError(page))) SetPageUptodate(page); } unlock_page(page); return; still_busy: bit_spin_unlock(BH_Uptodate_Lock, &first->b_state); local_irq_restore(flags); return; } /** * ntfs_read_block - fill a @page of an address space with data * @page: page cache page to fill with data * * Fill the page @page of the address space belonging to the @page->host inode. * We read each buffer asynchronously and when all buffers are read in, our io * completion handler ntfs_end_buffer_read_async(), if required, automatically * applies the mst fixups to the page before finally marking it uptodate and * unlocking it. * * We only enforce allocated_size limit because i_size is checked for in * generic_file_read(). * * Return 0 on success and -errno on error. * * Contains an adapted version of fs/buffer.c::block_read_full_page(). */ static int ntfs_read_block(struct page *page) { loff_t i_size; VCN vcn; LCN lcn; s64 init_size; struct inode *vi; ntfs_inode *ni; ntfs_volume *vol; runlist_element *rl; struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE]; sector_t iblock, lblock, zblock; unsigned long flags; unsigned int blocksize, vcn_ofs; int i, nr; unsigned char blocksize_bits; vi = page->mapping->host; ni = NTFS_I(vi); vol = ni->vol; /* $MFT/$DATA must have its complete runlist in memory at all times. */ BUG_ON(!ni->runlist.rl && !ni->mft_no && !NInoAttr(ni)); blocksize = vol->sb->s_blocksize; blocksize_bits = vol->sb->s_blocksize_bits; if (!page_has_buffers(page)) { create_empty_buffers(page, blocksize, 0); if (unlikely(!page_has_buffers(page))) { unlock_page(page); return -ENOMEM; } } bh = head = page_buffers(page); BUG_ON(!bh); /* * We may be racing with truncate. To avoid some of the problems we * now take a snapshot of the various sizes and use those for the whole * of the function. In case of an extending truncate it just means we * may leave some buffers unmapped which are now allocated. This is * not a problem since these buffers will just get mapped when a write * occurs. In case of a shrinking truncate, we will detect this later * on due to the runlist being incomplete and if the page is being * fully truncated, truncate will throw it away as soon as we unlock * it so no need to worry what we do with it. */ iblock = (s64)page->index << (PAGE_CACHE_SHIFT - blocksize_bits); read_lock_irqsave(&ni->size_lock, flags); lblock = (ni->allocated_size + blocksize - 1) >> blocksize_bits; init_size = ni->initialized_size; i_size = i_size_read(vi); read_unlock_irqrestore(&ni->size_lock, flags); if (unlikely(init_size > i_size)) { /* Race with shrinking truncate. */ init_size = i_size; } zblock = (init_size + blocksize - 1) >> blocksize_bits; /* Loop through all the buffers in the page. */ rl = NULL; nr = i = 0; do { int err = 0; if (unlikely(buffer_uptodate(bh))) continue; if (unlikely(buffer_mapped(bh))) { arr[nr++] = bh; continue; } bh->b_bdev = vol->sb->s_bdev; /* Is the block within the allowed limits? */ if (iblock < lblock) { bool is_retry = false; /* Convert iblock into corresponding vcn and offset. */ vcn = (VCN)iblock << blocksize_bits >> vol->cluster_size_bits; vcn_ofs = ((VCN)iblock << blocksize_bits) & vol->cluster_size_mask; 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; /* Successful remap. */ if (lcn >= 0) { /* Setup buffer head to correct block. */ bh->b_blocknr = ((lcn << vol->cluster_size_bits) + vcn_ofs) >> blocksize_bits; set_buffer_mapped(bh); /* Only read initialized data blocks. */ if (iblock < zblock) { arr[nr++] = bh; continue; } /* Fully non-initialized data block, zero it. */ goto handle_zblock; } /* It is a hole, need to zero it. */ if (lcn == LCN_HOLE) goto handle_hole; /* If first try and runlist unmapped, map and retry. */ if (!is_retry && lcn == LCN_RL_NOT_MAPPED) { is_retry = true; /* * Attempt to map runlist, dropping lock for * the duration. */ up_read(&ni->runlist.lock); err = ntfs_map_runlist(ni, vcn); if (likely(!err)) goto lock_retry_remap; rl = NULL; } else if (!rl) up_read(&ni->runlist.lock); /* * If buffer is outside the runlist, treat it as a * hole. This can happen due to concurrent truncate * for example. */ if (err == -ENOENT || lcn == LCN_ENOENT) { err = 0; goto handle_hole; } /* Hard error, zero out region. */ if (!err) err = -EIO; bh->b_blocknr = -1; SetPageError(page); ntfs_error(vol->sb, "Failed to read from inode 0x%lx, " "attribute type 0x%x, vcn 0x%llx, " "offset 0x%x because its location on " "disk could not be determined%s " "(error code %i).", ni->mft_no, ni->type, (unsigned long long)vcn, vcn_ofs, is_retry ? " even after " "retrying" : "", err); } /* * Either iblock was outside lblock limits or * ntfs_rl_vcn_to_lcn() returned error. Just zero that portion * of the page and set the buffer uptodate. */ handle_hole: bh->b_blocknr = -1UL; clear_buffer_mapped(bh); handle_zblock: zero_user(page, i * blocksize, blocksize); if (likely(!err)) set_buffer_uptodate(bh); } while (i++, iblock++, (bh = bh->b_this_page) != head); /* Release the lock if we took it. */ if (rl) up_read(&ni->runlist.lock); /* Check we have at least one buffer ready for i/o. */ if (nr) { struct buffer_head *tbh; /* Lock the buffers. */ for (i = 0; i < nr; i++) { tbh = arr[i]; lock_buffer(tbh); tbh->b_end_io = ntfs_end_buffer_async_read; set_buffer_async_read(tbh); } /* Finally, start i/o on the buffers. */ for (i = 0; i < nr; i++) { tbh = arr[i]; if (likely(!buffer_uptodate(tbh))) submit_bh(READ, tbh); else ntfs_end_buffer_async_read(tbh, 1); } return 0; } /* No i/o was scheduled on any of the buffers. */ if (likely(!PageError(page))) SetPageUptodate(page); else /* Signal synchronous i/o error. */ nr = -EIO; unlock_page(page); return nr; } /** * ntfs_readpage - fill a @page of a @file with data from the device * @file: open file to which the page @page belongs or NULL * @page: page cache page to fill with data * * For non-resident attributes, ntfs_readpage() fills the @page of the open * file @file by calling the ntfs version of the generic block_read_full_page() * function, ntfs_read_block(), which in turn creates and reads in the buffers * associated with the page asynchronously. * * For resident attributes, OTOH, ntfs_readpage() fills @page by copying the * data from the mft record (which at this stage is most likely in memory) and * fills the remainder with zeroes. Thus, in this case, I/O is synchronous, as * even if the mft record is not cached at this point in time, we need to wait * for it to be read in before we can do the copy. * * Return 0 on success and -errno on error. */ static int ntfs_readpage(struct file *file, struct page *page) { loff_t i_size; struct inode *vi; ntfs_inode *ni, *base_ni; u8 *addr; ntfs_attr_search_ctx *ctx; MFT_RECORD *mrec; unsigned long flags; u32 attr_len; int err = 0; retry_readpage: BUG_ON(!PageLocked(page)); vi = page->mapping->host; i_size = i_size_read(vi); /* Is the page fully outside i_size? (truncate in progress) */ if (unlikely(page->index >= (i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT)) { zero_user(page, 0, PAGE_CACHE_SIZE); ntfs_debug("Read outside i_size - truncated?"); goto done; } /* * This can potentially happen because we clear PageUptodate() during * ntfs_writepage() of MstProtected() attributes. */ if (PageUptodate(page)) { unlock_page(page); return 0; } ni = NTFS_I(vi); /* * Only $DATA attributes can be encrypted and only unnamed $DATA * attributes can be compressed. Index root can have the flags set but * this means to create compressed/encrypted files, not that the * attribute is compressed/encrypted. Note we need to check for * AT_INDEX_ALLOCATION since this is the type of both directory and * index inodes. */ if (ni->type != AT_INDEX_ALLOCATION) { /* If attribute is encrypted, deny access, just like NT4. */ if (NInoEncrypted(ni)) { BUG_ON(ni->type != AT_DATA); err = -EACCES; goto err_out; } /* Compressed data streams are handled in compress.c. */ if (NInoNonResident(ni) && NInoCompressed(ni)) { BUG_ON(ni->type != AT_DATA); BUG_ON(ni->name_len); return ntfs_read_compressed_block(page); } } /* NInoNonResident() == NInoIndexAllocPresent() */ if (NInoNonResident(ni)) { /* Normal, non-resident data stream. */ return ntfs_read_block(page); } /* * Attribute is resident, implying it is not compressed or encrypted. * This also means the attribute is smaller than an mft record and * hence smaller than a page, so can simply zero out any pages with * index above 0. Note the attribute can actually be marked compressed * but if it is resident the actual data is not compressed so we are * ok to ignore the compressed flag here. */ if (unlikely(page->index > 0)) { zero_user(page, 0, PAGE_CACHE_SIZE); goto done; } if (!NInoAttr(ni)) base_ni = ni; else base_ni = ni->ext.base_ntfs_ino; /* Map, pin, and lock the mft record. */ mrec = map_mft_record(base_ni); if (IS_ERR(mrec)) { err = PTR_ERR(mrec); goto err_out; } /* * If a parallel write made the attribute non-resident, drop the mft * record and retry the readpage. */ if (unlikely(NInoNonResident(ni))) { unmap_mft_record(base_ni); goto retry_readpage; } ctx = ntfs_attr_get_search_ctx(base_ni, mrec); if (unlikely(!ctx)) { err = -ENOMEM; goto unm_err_out; } err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len, CASE_SENSITIVE, 0, NULL, 0, ctx); if (unlikely(err)) goto put_unm_err_out; attr_len = le32_to_cpu(ctx->attr->data.resident.value_length); read_lock_irqsave(&ni->size_lock, flags); if (unlikely(attr_len > ni->initialized_size)) attr_len = ni->initialized_size; i_size = i_size_read(vi); read_unlock_irqrestore(&ni->size_lock, flags); if (unlikely(attr_len > i_size)) { /* Race with shrinking truncate. */ attr_len = i_size; } addr = kmap_atomic(page, KM_USER0); /* Copy the data to the page. */ memcpy(addr, (u8*)ctx->attr + le16_to_cpu(ctx->attr->data.resident.value_offset), attr_len); /* Zero the remainder of the page. */ memset(addr + attr_len, 0, PAGE_CACHE_SIZE - attr_len); flush_dcache_page(page); kunmap_atomic(addr, KM_USER0); put_unm_err_out: ntfs_attr_put_search_ctx(ctx); unm_err_out: unmap_mft_record(base_ni); done: SetPageUptodate(page); err_out: unlock_page(page); return err; } #ifdef NTFS_RW /** * ntfs_write_block - write a @page to the backing store * @page: page cache page to write out * @wbc: writeback control structure * * This function is for writing pages belonging to non-resident, non-mst * protected attributes to their backing store. * * For a page with buffers, map and write the dirty buffers asynchronously * under page writeback. For a page without buffers, create buffers for the * page, then proceed as above. * * If a page doesn't have buffers the page dirty state is definitive. If a page * does have buffers, the page dirty state is just a hint, and the buffer dirty * state is definitive. (A hint which has rules: dirty buffers against a clean * page is illegal. Other combinations are legal and need to be handled. In * particular a dirty page containing clean buffers for example.) * * Return 0 on success and -errno on error. * * Based on ntfs_read_block() and __block_write_full_page(). */ static int ntfs_write_block(struct page *page, struct writeback_control *wbc) { VCN vcn; LCN lcn; s64 initialized_size; loff_t i_size; sector_t block, dblock, iblock; struct inode *vi; ntfs_inode *ni; ntfs_volume *vol; runlist_element *rl; struct buffer_head *bh, *head; unsigned long flags; unsigned int blocksize, vcn_ofs; int err; bool need_end_writeback; unsigned char blocksize_bits; vi = page->mapping->host; ni = NTFS_I(vi); vol = ni->vol; ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, page index " "0x%lx.", ni->mft_no, ni->type, page->index); BUG_ON(!NInoNonResident(ni)); BUG_ON(NInoMstProtected(ni)); blocksize = vol->sb->s_blocksize; blocksize_bits = vol->sb->s_blocksize_bits; if (!page_has_buffers(page)) { BUG_ON(!PageUptodate(page)); create_empty_buffers(page, blocksize, (1 << BH_Uptodate) | (1 << BH_Dirty)); if (unlikely(!page_has_buffers(page))) { ntfs_warning(vol->sb, "Error allocating page " "buffers. Redirtying page so we try " "again later."); /* * Put the page back on mapping->dirty_pages, but leave * its buffers' dirty state as-is. */ redirty_page_for_writepage(wbc, page); unlock_page(page); return 0; } } bh = head = page_buffers(page); BUG_ON(!bh); /* NOTE: Different naming scheme to ntfs_read_block()! */ /* The first block in the page. */ block = (s64)page->index << (PAGE_CACHE_SHIFT - blocksize_bits); read_lock_irqsave(&ni->size_lock, flags); i_size = i_size_read(vi); initialized_size = ni->initialized_size; read_unlock_irqrestore(&ni->size_lock, flags); /* The first out of bounds block for the data size. */ dblock = (i_size + blocksize - 1) >> blocksize_bits; /* The last (fully or partially) initialized block. */ iblock = initialized_size >> blocksize_bits; /* * Be very careful. We have no exclusion from __set_page_dirty_buffers * here, and the (potentially unmapped) buffers may become dirty at * any time. If a buffer becomes dirty here after we've inspected it * then we just miss that fact, and the page stays dirty. * * Buffers outside i_size may be dirtied by __set_page_dirty_buffers; * handle that here by just cleaning them. */ /* * Loop through all the buffers in the page, mapping all the dirty * buffers to disk addresses and handling any aliases from the * underlying block device's mapping. */ rl = NULL; err = 0; do { bool is_retry = false; if (unlikely(block >= dblock)) { /* * Mapped buffers outside i_size will occur, because * this page can be outside i_size when there is a * truncate in progress. The contents of such buffers * were zeroed by ntfs_writepage(). * * FIXME: What about the small race window where * ntfs_writepage() has not done any clearing because * the page was within i_size but before we get here, * vmtruncate() modifies i_size? */ clear_buffer_dirty(bh); set_buffer_uptodate(bh); continue; } /* Clean buffers are not written out, so no need to map them. */ if (!buffer_dirty(bh)) continue; /* Make sure we have enough initialized size. */ if (unlikely((block >= iblock) && (initialized_size < i_size))) { /* * If this page is fully outside initialized size, zero * out all pages between the current initialized size * and the current page. Just use ntfs_readpage() to do * the zeroing transparently. */ if (block > iblock) { // TODO: // For each page do: // - read_cache_page() // Again for each page do: // - wait_on_page_locked() // - Check (PageUptodate(page) && // !PageError(page)) // Update initialized size in the attribute and // in the inode. // Again, for each page do: // __set_page_dirty_buffers(); // page_cache_release() // We don't need to wait on the writes. // Update iblock. } /* * The current page straddles initialized size. Zero * all non-uptodate buffers and set them uptodate (and * dirty?). Note, there aren't any non-uptodate buffers * if the page is uptodate. * FIXME: For an uptodate page, the buffers may need to * be written out because they were not initialized on * disk before. */ if (!PageUptodate(page)) { // TODO: // Zero any non-uptodate buffers up to i_size. // Set them uptodate and dirty. } // TODO: // Update initialized size in the attribute and in the // inode (up to i_size). // Update iblock. // FIXME: This is inefficient. Try to batch the two // size changes to happen in one go. ntfs_error(vol->sb, "Writing beyond initialized size " "is not supported yet. Sorry."); err = -EOPNOTSUPP; break; // Do NOT set_buffer_new() BUT DO clear buffer range // outside write request range. // set_buffer_uptodate() on complete buffers as well as // set_buffer_dirty(). } /* No need to map buffers that are already mapped. */ if (buffer_mapped(bh)) continue; /* Unmapped, dirty buffer. Need to map it. */ bh->b_bdev = vol->sb->s_bdev; /* Convert block into corresponding vcn and offset. */ vcn = (VCN)block << blocksize_bits; vcn_ofs = vcn & vol->cluster_size_mask; vcn >>= vol->cluster_size_bits; 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; /* Successful remap. */ if (lcn >= 0) { /* Setup buffer head to point to correct block. */ bh->b_blocknr = ((lcn << vol->cluster_size_bits) + vcn_ofs) >> blocksize_bits; set_buffer_mapped(bh); continue; } /* It is a hole, need to instantiate it. */ if (lcn == LCN_HOLE) { u8 *kaddr; unsigned long *bpos, *bend; /* Check if the buffer is zero. */ kaddr = kmap_atomic(page, KM_USER0); bpos = (unsigned long *)(kaddr + bh_offset(bh)); bend = (unsigned long *)((u8*)bpos + blocksize); do { if (unlikely(*bpos)) break; } while (likely(++bpos < bend)); kunmap_atomic(kaddr, KM_USER0); if (bpos == bend) { /* * Buffer is zero and sparse, no need to write * it. */ bh->b_blocknr = -1; clear_buffer_dirty(bh); continue; } // TODO: Instantiate the hole. // clear_buffer_new(bh); // unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr); ntfs_error(vol->sb, "Writing into sparse regions is " "not supported yet. Sorry."); err = -EOPNOTSUPP; break; } /* If first try and runlist unmapped, map and retry. */ if (!is_retry && lcn == LCN_RL_NOT_MAPPED) { is_retry = true; /* * Attempt to map runlist, dropping lock for * the duration. */ up_read(&ni->runlist.lock); err = ntfs_map_runlist(ni, vcn); if (likely(!err)) goto lock_retry_remap; rl = NULL; } else if (!rl) up_read(&ni->runlist.lock); /* * If buffer is outside the runlist, truncate has cut it out * of the runlist. Just clean and clear the buffer and set it * uptodate so it can get discarded by the VM. */ if (err == -ENOENT || lcn == LCN_ENOENT) { bh->b_blocknr = -1; clear_buffer_dirty(bh); zero_user(page, bh_offset(bh), blocksize); set_buffer_uptodate(bh); err = 0; continue; } /* Failed to map the buffer, even after retrying. */ if (!err) err = -EIO; bh->b_blocknr = -1; ntfs_error(vol->sb, "Failed to write to inode 0x%lx, " "attribute type 0x%x, vcn 0x%llx, offset 0x%x " "because its location on disk could not be " "determined%s (error code %i).", ni->mft_no, ni->type, (unsigned long long)vcn, vcn_ofs, is_retry ? " even after " "retrying" : "", err); break; } while (block++, (bh = bh->b_this_page) != head); /* Release the lock if we took it. */ if (rl) up_read(&ni->runlist.lock); /* For the error case, need to reset bh to the beginning. */ bh = head; /* Just an optimization, so ->readpage() is not called later. */ if (unlikely(!PageUptodate(page))) { int uptodate = 1; do { if (!buffer_uptodate(bh)) { uptodate = 0; bh = head; break; } } while ((bh = bh->b_this_page) != head); if (uptodate) SetPageUptodate(page); } /* Setup all mapped, dirty buffers for async write i/o. */ do { if (buffer_mapped(bh) && buffer_dirty(bh)) { lock_buffer(bh); if (test_clear_buffer_dirty(bh)) { BUG_ON(!buffer_uptodate(bh)); mark_buffer_async_write(bh); } else unlock_buffer(bh); } else if (unlikely(err)) { /* * For the error case. The buffer may have been set * dirty during attachment to a dirty page. */ if (err != -ENOMEM) clear_buffer_dirty(bh); } } while ((bh = bh->b_this_page) != head); if (unlikely(err)) { // TODO: Remove the -EOPNOTSUPP check later on... if (unlikely(err == -EOPNOTSUPP)) err = 0; else if (err == -ENOMEM) { ntfs_warning(vol->sb, "Error allocating memory. " "Redirtying page so we try again " "later."); /* * Put the page back on mapping->dirty_pages, but * leave its buffer's dirty state as-is. */ redirty_page_for_writepage(wbc, page); err = 0; } else SetPageError(page); } BUG_ON(PageWriteback(page)); set_page_writeback(page); /* Keeps try_to_free_buffers() away. */ /* Submit the prepared buffers for i/o. */ need_end_writeback = true; do { struct buffer_head *next = bh->b_this_page; if (buffer_async_write(bh)) { submit_bh(WRITE, bh); need_end_writeback = false; } bh = next; } while (bh != head); unlock_page(page); /* If no i/o was started, need to end_page_writeback(). */ if (unlikely(need_end_writeback)) end_page_writeback(page); ntfs_debug("Done."); return err; } /** * ntfs_write_mst_block - write a @page to the backing store * @page: page cache page to write out * @wbc: writeback control structure * * This function is for writing pages belonging to non-resident, mst protected * attributes to their backing store. The only supported attributes are index * allocation and $MFT/$DATA. Both directory inodes and index inodes are * supported for the index allocation case. * * The page must remain locked for the duration of the write because we apply * the mst fixups, write, and then undo the fixups, so if we were to unlock the * page before undoing the fixups, any other user of the page will see the * page contents as corrupt. * * We clear the page uptodate flag for the duration of the function to ensure * exclusion for the $MFT/$DATA case against someone mapping an mft record we * are about to apply the mst fixups to. * * Return 0 on success and -errno on error. * * Based on ntfs_write_block(), ntfs_mft_writepage(), and * write_mft_record_nolock(). */ static int ntfs_write_mst_block(struct page *page, struct writeback_control *wbc) { sector_t block, dblock, rec_block; struct inode *vi = page->mapping->host; ntfs_inode *ni = NTFS_I(vi); ntfs_volume *vol = ni->vol; u8 *kaddr; unsigned int rec_size = ni->itype.index.block_size; ntfs_inode *locked_nis[PAGE_CACHE_SIZE / rec_size]; struct buffer_head *bh, *head, *tbh, *rec_start_bh; struct buffer_head *bhs[MAX_BUF_PER_PAGE]; runlist_element *rl; int i, nr_locked_nis, nr_recs, nr_bhs, max_bhs, bhs_per_rec, err, err2; unsigned bh_size, rec_size_bits; bool sync, is_mft, page_is_dirty, rec_is_dirty; unsigned char bh_size_bits; ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, page index " "0x%lx.", vi->i_ino, ni->type, page->index); BUG_ON(!NInoNonResident(ni)); BUG_ON(!NInoMstProtected(ni)); is_mft = (S_ISREG(vi->i_mode) && !vi->i_ino); /* * NOTE: ntfs_write_mst_block() would be called for $MFTMirr if a page * in its page cache were to be marked dirty. However this should * never happen with the current driver and considering we do not * handle this case here we do want to BUG(), at least for now. */ BUG_ON(!(is_mft || S_ISDIR(vi->i_mode) || (NInoAttr(ni) && ni->type == AT_INDEX_ALLOCATION))); bh_size = vol->sb->s_blocksize; bh_size_bits = vol->sb->s_blocksize_bits; max_bhs = PAGE_CACHE_SIZE / bh_size; BUG_ON(!max_bhs); BUG_ON(max_bhs > MAX_BUF_PER_PAGE); /* Were we called for sync purposes? */ sync = (wbc->sync_mode == WB_SYNC_ALL); /* Make sure we have mapped buffers. */ bh = head = page_buffers(page); BUG_ON(!bh); rec_size_bits = ni->itype.index.block_size_bits; BUG_ON(!(PAGE_CACHE_SIZE >> rec_size_bits)); bhs_per_rec = rec_size >> bh_size_bits; BUG_ON(!bhs_per_rec); /* The first block in the page. */ rec_block = block = (sector_t)page->index << (PAGE_CACHE_SHIFT - bh_size_bits); /* The first out of bounds block for the data size. */ dblock = (i_size_read(vi) + bh_size - 1) >> bh_size_bits; rl = NULL; err = err2 = nr_bhs = nr_recs = nr_locked_nis = 0; page_is_dirty = rec_is_dirty = false; rec_start_bh = NULL; do { bool is_retry = false; if (likely(block < rec_block)) { if (unlikely(block >= dblock)) { clear_buffer_dirty(bh); set_buffer_uptodate(bh); continue; } /* * This block is not the first one in the record. We * ignore the buffer's dirty state because we could * have raced with a parallel mark_ntfs_record_dirty(). */ if (!rec_is_dirty) continue; if (unlikely(err2)) { if (err2 != -ENOMEM) clear_buffer_dirty(bh); continue; } } else /* if (block == rec_block) */ { BUG_ON(block > rec_block); /* This block is the first one in the record. */ rec_block += bhs_per_rec; err2 = 0; if (unlikely(block >= dblock)) { clear_buffer_dirty(bh); continue; } if (!buffer_dirty(bh)) { /* Clean records are not written out. */ rec_is_dirty = false; continue; } rec_is_dirty = true; rec_start_bh = bh; } /* Need to map the buffer if it is not mapped already. */ if (unlikely(!buffer_mapped(bh))) { VCN vcn; LCN lcn; unsigned int vcn_ofs; bh->b_bdev = vol->sb->s_bdev; /* Obtain the vcn and offset of the current block. */ vcn = (VCN)block << bh_size_bits; vcn_ofs = vcn & vol->cluster_size_mask; vcn >>= vol->cluster_size_bits; 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; /* Successful remap. */ if (likely(lcn >= 0)) { /* Setup buffer head to correct block. */ bh->b_blocknr = ((lcn << vol->cluster_size_bits) + vcn_ofs) >> bh_size_bits; set_buffer_mapped(bh); } else { /* * Remap failed. Retry to map the runlist once * unless we are working on $MFT which always * has the whole of its runlist in memory. */ if (!is_mft && !is_retry && lcn == LCN_RL_NOT_MAPPED) { is_retry = true; /* * Attempt to map runlist, dropping * lock for the duration. */ up_read(&ni->runlist.lock); err2 = ntfs_map_runlist(ni, vcn); if (likely(!err2)) goto lock_retry_remap; if (err2 == -ENOMEM) page_is_dirty = true; lcn = err2; } else { err2 = -EIO; if (!rl) up_read(&ni->runlist.lock); } /* Hard error. Abort writing this record. */ if (!err || err == -ENOMEM) err = err2; bh->b_blocknr = -1; ntfs_error(vol->sb, "Cannot write ntfs record " "0x%llx (inode 0x%lx, " "attribute type 0x%x) because " "its location on disk could " "not be determined (error " "code %lli).", (long long)block << bh_size_bits >> vol->mft_record_size_bits, ni->mft_no, ni->type, (long long)lcn); /* * If this is not the first buffer, remove the * buffers in this record from the list of * buffers to write and clear their dirty bit * if not error -ENOMEM. */ if (rec_start_bh != bh) { while (bhs[--nr_bhs] != rec_start_bh) ; if (err2 != -ENOMEM) { do { clear_buffer_dirty( rec_start_bh); } while ((rec_start_bh = rec_start_bh-> b_this_page) != bh); } } continue; } } BUG_ON(!buffer_uptodate(bh)); BUG_ON(nr_bhs >= max_bhs); bhs[nr_bhs++] = bh; } while (block++, (bh = bh->b_this_page) != head); if (unlikely(rl)) up_read(&ni->runlist.lock); /* If there were no dirty buffers, we are done. */ if (!nr_bhs) goto done; /* Map the page so we can access its contents. */ kaddr = kmap(page); /* Clear the page uptodate flag whilst the mst fixups are applied. */ BUG_ON(!PageUptodate(page)); ClearPageUptodate(page); for (i = 0; i < nr_bhs; i++) { unsigned int ofs; /* Skip buffers which are not at the beginning of records. */ if (i % bhs_per_rec) continue; tbh = bhs[i]; ofs = bh_offset(tbh); if (is_mft) { ntfs_inode *tni; unsigned long mft_no; /* Get the mft record number. */ mft_no = (((s64)page->index << PAGE_CACHE_SHIFT) + ofs) >> rec_size_bits; /* Check whether to write this mft record. */ tni = NULL; if (!ntfs_may_write_mft_record(vol, mft_no, (MFT_RECORD*)(kaddr + ofs), &tni)) { /* * The record should not be written. This * means we need to redirty the page before * returning. */ page_is_dirty = true; /* * Remove the buffers in this mft record from * the list of buffers to write. */ do { bhs[i] = NULL; } while (++i % bhs_per_rec); continue; } /* * The record should be written. If a locked ntfs * inode was returned, add it to the array of locked * ntfs inodes. */ if (tni) locked_nis[nr_locked_nis++] = tni; } /* Apply the mst protection fixups. */ err2 = pre_write_mst_fixup((NTFS_RECORD*)(kaddr + ofs), rec_size); if (unlikely(err2)) { if (!err || err == -ENOMEM) err = -EIO; ntfs_error(vol->sb, "Failed to apply mst fixups " "(inode 0x%lx, attribute type 0x%x, " "page index 0x%lx, page offset 0x%x)!" " Unmount and run chkdsk.", vi->i_ino, ni->type, page->index, ofs); /* * Mark all the buffers in this record clean as we do * not want to write corrupt data to disk. */ do { clear_buffer_dirty(bhs[i]); bhs[i] = NULL; } while (++i % bhs_per_rec); continue; } nr_recs++; } /* If no records are to be written out, we are done. */ if (!nr_recs) goto unm_done; flush_dcache_page(page); /* Lock buffers and start synchronous write i/o on them. */ for (i = 0; i < nr_bhs; i++) { tbh = bhs[i]; if (!tbh) continue; if (!trylock_buffer(tbh)) BUG(); /* The buffer dirty state is now irrelevant, just clean it. */ clear_buffer_dirty(tbh); BUG_ON(!buffer_uptodate(tbh)); BUG_ON(!buffer_mapped(tbh)); get_bh(tbh); tbh->b_end_io = end_buffer_write_sync; submit_bh(WRITE, tbh); } /* Synchronize the mft mirror now if not @sync. */ if (is_mft && !sync) goto do_mirror; do_wait: /* Wait on i/o completion of buffers. */ for (i = 0; i < nr_bhs; i++) { tbh = bhs[i]; if (!tbh) continue; wait_on_buffer(tbh); if (unlikely(!buffer_uptodate(tbh))) { ntfs_error(vol->sb, "I/O error while writing ntfs " "record buffer (inode 0x%lx, " "attribute type 0x%x, page index " "0x%lx, page offset 0x%lx)! Unmount " "and run chkdsk.", vi->i_ino, ni->type, page->index, bh_offset(tbh)); if (!err || err == -ENOMEM) err = -EIO; /* * Set the buffer uptodate so the page and buffer * states do not become out of sync. */ set_buffer_uptodate(tbh); } } /* If @sync, now synchronize the mft mirror. */ if (is_mft && sync) { do_mirror: for (i = 0; i < nr_bhs; i++) { unsigned long mft_no; unsigned int ofs; /* * Skip buffers which are not at the beginning of * records. */ if (i % bhs_per_rec) continue; tbh = bhs[i]; /* Skip removed buffers (and hence records). */ if (!tbh) continue; ofs = bh_offset(tbh); /* Get the mft record number. */ mft_no = (((s64)page->index << PAGE_CACHE_SHIFT) + ofs) >> rec_size_bits; if (mft_no < vol->mftmirr_size) ntfs_sync_mft_mirror(vol, mft_no, (MFT_RECORD*)(kaddr + ofs), sync); } if (!sync) goto do_wait; } /* Remove the mst protection fixups again. */ for (i = 0; i < nr_bhs; i++) { if (!(i % bhs_per_rec)) { tbh = bhs[i]; if (!tbh) continue; post_write_mst_fixup((NTFS_RECORD*)(kaddr + bh_offset(tbh))); } } flush_dcache_page(page); unm_done: /* Unlock any locked inodes. */ while (nr_locked_nis-- > 0) { ntfs_inode *tni, *base_tni; tni = locked_nis[nr_locked_nis]; /* Get the base inode. */ mutex_lock(&tni->extent_lock); if (tni->nr_extents >= 0) base_tni = tni; else { base_tni = tni->ext.base_ntfs_ino; BUG_ON(!base_tni); } mutex_unlock(&tni->extent_lock); ntfs_debug("Unlocking %s inode 0x%lx.", tni == base_tni ? "base" : "extent", tni->mft_no); mutex_unlock(&tni->mrec_lock); atomic_dec(&tni->count); iput(VFS_I(base_tni)); } SetPageUptodate(page); kunmap(page); done: if (unlikely(err && err != -ENOMEM)) { /* * Set page error if there is only one ntfs record in the page. * Otherwise we would loose per-record granularity. */ if (ni->itype.index.block_size == PAGE_CACHE_SIZE) SetPageError(page); NVolSetErrors(vol); } if (page_is_dirty) { ntfs_debug("Page still contains one or more dirty ntfs " "records. Redirtying the page starting at " "record 0x%lx.", page->index << (PAGE_CACHE_SHIFT - rec_size_bits)); redirty_page_for_writepage(wbc, page); unlock_page(page); } else { /* * Keep the VM happy. This must be done otherwise the * radix-tree tag PAGECACHE_TAG_DIRTY remains set even though * the page is clean. */ BUG_ON(PageWriteback(page)); set_page_writeback(page); unlock_page(page); end_page_writeback(page); } if (likely(!err)) ntfs_debug("Done."); return err; } /** * ntfs_writepage - write a @page to the backing store * @page: page cache page to write out * @wbc: writeback control structure * * This is called from the VM when it wants to have a dirty ntfs page cache * page cleaned. The VM has already locked the page and marked it clean. * * For non-resident attributes, ntfs_writepage() writes the @page by calling * the ntfs version of the generic block_write_full_page() function, * ntfs_write_block(), which in turn if necessary creates and writes the * buffers associated with the page asynchronously. * * For resident attributes, OTOH, ntfs_writepage() writes the @page by copying * the data to the mft record (which at this stage is most likely in memory). * The mft record is then marked dirty and written out asynchronously via the * vfs inode dirty code path for the inode the mft record belongs to or via the * vm page dirty code path for the page the mft record is in. * * Based on ntfs_readpage() and fs/buffer.c::block_write_full_page(). * * Return 0 on success and -errno on error. */ static int ntfs_writepage(struct page *page, struct writeback_control *wbc) { loff_t i_size; struct inode *vi = page->mapping->host; ntfs_inode *base_ni = NULL, *ni = NTFS_I(vi); char *addr; ntfs_attr_search_ctx *ctx = NULL; MFT_RECORD *m = NULL; u32 attr_len; int err; retry_writepage: BUG_ON(!PageLocked(page)); i_size = i_size_read(vi); /* Is the page fully outside i_size? (truncate in progress) */ if (unlikely(page->index >= (i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT)) { /* * The page may have dirty, unmapped buffers. Make them * freeable here, so the page does not leak. */ block_invalidatepage(page, 0); unlock_page(page); ntfs_debug("Write outside i_size - truncated?"); return 0; } /* * Only $DATA attributes can be encrypted and only unnamed $DATA * attributes can be compressed. Index root can have the flags set but * this means to create compressed/encrypted files, not that the * attribute is compressed/encrypted. Note we need to check for * AT_INDEX_ALLOCATION since this is the type of both directory and * index inodes. */ if (ni->type != AT_INDEX_ALLOCATION) { /* If file is encrypted, deny access, just like NT4. */ if (NInoEncrypted(ni)) { unlock_page(page); BUG_ON(ni->type != AT_DATA); ntfs_debug("Denying write access to encrypted file."); return -EACCES; } /* Compressed data streams are handled in compress.c. */ if (NInoNonResident(ni) && NInoCompressed(ni)) { BUG_ON(ni->type != AT_DATA); BUG_ON(ni->name_len); // TODO: Implement and replace this with // return ntfs_write_compressed_block(page); unlock_page(page); ntfs_error(vi->i_sb, "Writing to compressed files is " "not supported yet. Sorry."); return -EOPNOTSUPP; } // TODO: Implement and remove this check. if (NInoNonResident(ni) && NInoSparse(ni)) { unlock_page(page); ntfs_error(vi->i_sb, "Writing to sparse files is not " "supported yet. Sorry."); return -EOPNOTSUPP; } } /* NInoNonResident() == NInoIndexAllocPresent() */ if (NInoNonResident(ni)) { /* We have to zero every time due to mmap-at-end-of-file. */ if (page->index >= (i_size >> PAGE_CACHE_SHIFT)) { /* The page straddles i_size. */ unsigned int ofs = i_size & ~PAGE_CACHE_MASK; zero_user_segment(page, ofs, PAGE_CACHE_SIZE); } /* Handle mst protected attributes. */ if (NInoMstProtected(ni)) return ntfs_write_mst_block(page, wbc); /* Normal, non-resident data stream. */ return ntfs_write_block(page, wbc); } /* * Attribute is resident, implying it is not compressed, encrypted, or * mst protected. This also means the attribute is smaller than an mft * record and hence smaller than a page, so can simply return error on * any pages with index above 0. Note the attribute can actually be * marked compressed but if it is resident the actual data is not * compressed so we are ok to ignore the compressed flag here. */ BUG_ON(page_has_buffers(page)); BUG_ON(!PageUptodate(page)); if (unlikely(page->index > 0)) { ntfs_error(vi->i_sb, "BUG()! page->index (0x%lx) > 0. " "Aborting write.", page->index); BUG_ON(PageWriteback(page)); set_page_writeback(page); unlock_page(page); end_page_writeback(page); return -EIO; } if (!NInoAttr(ni)) base_ni = ni; else base_ni = ni->ext.base_ntfs_ino; /* Map, pin, and lock the mft record. */ m = map_mft_record(base_ni); if (IS_ERR(m)) { err = PTR_ERR(m); m = NULL; ctx = NULL; goto err_out; } /* * If a parallel write made the attribute non-resident, drop the mft * record and retry the writepage. */ if (unlikely(NInoNonResident(ni))) { unmap_mft_record(base_ni); goto retry_writepage; } ctx = ntfs_attr_get_search_ctx(base_ni, m); if (unlikely(!ctx)) { err = -ENOMEM; goto err_out; } err = ntfs_attr_lookup(ni->type, ni->name, ni->name_len, CASE_SENSITIVE, 0, NULL, 0, ctx); if (unlikely(err)) goto err_out; /* * Keep the VM happy. This must be done otherwise the radix-tree tag * PAGECACHE_TAG_DIRTY remains set even though the page is clean. */ BUG_ON(PageWriteback(page)); set_page_writeback(page); unlock_page(page); attr_len = le32_to_cpu(ctx->attr->data.resident.value_length); i_size = i_size_read(vi); if (unlikely(attr_len > i_size)) { /* Race with shrinking truncate or a failed truncate. */ attr_len = i_size; /* * If the truncate failed, fix it up now. If a concurrent * truncate, we do its job, so it does not have to do anything. */ err = ntfs_resident_attr_value_resize(ctx->mrec, ctx->attr, attr_len); /* Shrinking cannot fail. */ BUG_ON(err); } addr = kmap_atomic(page, KM_USER0); /* Copy the data from the page to the mft record. */ memcpy((u8*)ctx->attr + le16_to_cpu(ctx->attr->data.resident.value_offset), addr, attr_len); /* Zero out of bounds area in the page cache page. */ memset(addr + attr_len, 0, PAGE_CACHE_SIZE - attr_len); kunmap_atomic(addr, KM_USER0); flush_dcache_page(page); flush_dcache_mft_record_page(ctx->ntfs_ino); /* We are done with the page. */ end_page_writeback(page); /* Finally, mark the mft record dirty, so it gets written back. */ mark_mft_record_dirty(ctx->ntfs_ino); ntfs_attr_put_search_ctx(ctx); unmap_mft_record(base_ni); return 0; err_out: if (err == -ENOMEM) { ntfs_warning(vi->i_sb, "Error allocating memory. Redirtying " "page so we try again later."); /* * Put the page back on mapping->dirty_pages, but leave its * buffers' dirty state as-is. */ redirty_page_for_writepage(wbc, page); err = 0; } else { ntfs_error(vi->i_sb, "Resident attribute write failed with " "error %i.", err); SetPageError(page); NVolSetErrors(ni->vol); } unlock_page(page); if (ctx) ntfs_attr_put_search_ctx(ctx); if (m) unmap_mft_record(base_ni); return err; } #endif /* NTFS_RW */ /** * ntfs_aops - general address space operations for inodes and attributes */ const struct address_space_operations ntfs_aops = { .readpage = ntfs_readpage, /* Fill page with data. */ #ifdef NTFS_RW .writepage = ntfs_writepage, /* Write dirty page to disk. */ #endif /* NTFS_RW */ .migratepage = buffer_migrate_page, /* Move a page cache page from one physical page to an other. */ .error_remove_page = generic_error_remove_page, }; /** * ntfs_mst_aops - general address space operations for mst protecteed inodes * and attributes */ const struct address_space_operations ntfs_mst_aops = { .readpage = ntfs_readpage, /* Fill page with data. */ #ifdef NTFS_RW .writepage = ntfs_writepage, /* Write dirty page to disk. */ .set_page_dirty = __set_page_dirty_nobuffers, /* Set the page dirty without touching the buffers belonging to the page. */ #endif /* NTFS_RW */ .migratepage = buffer_migrate_page, /* Move a page cache page from one physical page to an other. */ .error_remove_page = generic_error_remove_page, }; #ifdef NTFS_RW /** * mark_ntfs_record_dirty - mark an ntfs record dirty * @page: page containing the ntfs record to mark dirty * @ofs: byte offset within @page at which the ntfs record begins * * Set the buffers and the page in which the ntfs record is located dirty. * * The latter also marks the vfs inode the ntfs record belongs to dirty * (I_DIRTY_PAGES only). * * If the page does not have buffers, we create them and set them uptodate. * The page may not be locked which is why we need to handle the buffers under * the mapping->private_lock. Once the buffers are marked dirty we no longer * need the lock since try_to_free_buffers() does not free dirty buffers. */ void mark_ntfs_record_dirty(struct page *page, const unsigned int ofs) { struct address_space *mapping = page->mapping; ntfs_inode *ni = NTFS_I(mapping->host); struct buffer_head *bh, *head, *buffers_to_free = NULL; unsigned int end, bh_size, bh_ofs; BUG_ON(!PageUptodate(page)); end = ofs + ni->itype.index.block_size; bh_size = VFS_I(ni)->i_sb->s_blocksize; spin_lock(&mapping->private_lock); if (unlikely(!page_has_buffers(page))) { spin_unlock(&mapping->private_lock); bh = head = alloc_page_buffers(page, bh_size, 1); spin_lock(&mapping->private_lock); if (likely(!page_has_buffers(page))) { struct buffer_head *tail; do { set_buffer_uptodate(bh); tail = bh; bh = bh->b_this_page; } while (bh); tail->b_this_page = head; attach_page_buffers(page, head); } else buffers_to_free = bh; } bh = head = page_buffers(page); BUG_ON(!bh); do { bh_ofs = bh_offset(bh); if (bh_ofs + bh_size <= ofs) continue; if (unlikely(bh_ofs >= end)) break; set_buffer_dirty(bh); } while ((bh = bh->b_this_page) != head); spin_unlock(&mapping->private_lock); __set_page_dirty_nobuffers(page); if (unlikely(buffers_to_free)) { do { bh = buffers_to_free->b_this_page; free_buffer_head(buffers_to_free); buffers_to_free = bh; } while (buffers_to_free); } } #endif /* NTFS_RW */