diff options
Diffstat (limited to 'fs/ntfs/aops.c')
| -rw-r--r-- | fs/ntfs/aops.c | 2324 |
1 files changed, 2324 insertions, 0 deletions
diff --git a/fs/ntfs/aops.c b/fs/ntfs/aops.c new file mode 100644 index 000000000000..45d56e41ed98 --- /dev/null +++ b/fs/ntfs/aops.c @@ -0,0 +1,2324 @@ +/** + * aops.c - NTFS kernel address space operations and page cache 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/errno.h> +#include <linux/mm.h> +#include <linux/pagemap.h> +#include <linux/swap.h> +#include <linux/buffer_head.h> +#include <linux/writeback.h> + +#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) +{ + static DEFINE_SPINLOCK(page_uptodate_lock); + unsigned long flags; + struct buffer_head *tmp; + struct page *page; + ntfs_inode *ni; + int page_uptodate = 1; + + page = bh->b_page; + ni = NTFS_I(page->mapping->host); + + if (likely(uptodate)) { + s64 file_ofs; + + set_buffer_uptodate(bh); + + file_ofs = ((s64)page->index << PAGE_CACHE_SHIFT) + + bh_offset(bh); + /* Check for the current buffer head overflowing. */ + if (file_ofs + bh->b_size > ni->initialized_size) { + char *addr; + int ofs = 0; + + if (file_ofs < ni->initialized_size) + ofs = ni->initialized_size - file_ofs; + addr = kmap_atomic(page, KM_BIO_SRC_IRQ); + memset(addr + bh_offset(bh) + ofs, 0, bh->b_size - ofs); + flush_dcache_page(page); + kunmap_atomic(addr, KM_BIO_SRC_IRQ); + } + } else { + clear_buffer_uptodate(bh); + ntfs_error(ni->vol->sb, "Buffer I/O error, logical block %llu.", + (unsigned long long)bh->b_blocknr); + SetPageError(page); + } + spin_lock_irqsave(&page_uptodate_lock, flags); + 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); + spin_unlock_irqrestore(&page_uptodate_lock, 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 { + char *addr; + 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); + addr = kmap_atomic(page, KM_BIO_SRC_IRQ); + for (i = 0; i < recs; i++) + post_read_mst_fixup((NTFS_RECORD*)(addr + + i * rec_size), rec_size); + flush_dcache_page(page); + kunmap_atomic(addr, KM_BIO_SRC_IRQ); + if (likely(!PageError(page) && page_uptodate)) + SetPageUptodate(page); + } + unlock_page(page); + return; +still_busy: + spin_unlock_irqrestore(&page_uptodate_lock, 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) +{ + VCN vcn; + LCN lcn; + 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 int blocksize, vcn_ofs; + int i, nr; + unsigned char blocksize_bits; + + ni = NTFS_I(page->mapping->host); + 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_bits = VFS_I(ni)->i_blkbits; + blocksize = 1 << blocksize_bits; + + if (!page_has_buffers(page)) + create_empty_buffers(page, blocksize, 0); + bh = head = page_buffers(page); + if (unlikely(!bh)) { + unlock_page(page); + return -ENOMEM; + } + + iblock = (s64)page->index << (PAGE_CACHE_SHIFT - blocksize_bits); + lblock = (ni->allocated_size + blocksize - 1) >> blocksize_bits; + zblock = (ni->initialized_size + blocksize - 1) >> blocksize_bits; + + /* Loop through all the buffers in the page. */ + rl = NULL; + nr = i = 0; + do { + u8 *kaddr; + + 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) { + int err; + 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; + lcn = err; + } + /* Hard error, zero out region. */ + 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 %lli).", ni->mft_no, + ni->type, (unsigned long long)vcn, + vcn_ofs, is_retry ? " even after " + "retrying" : "", (long long)lcn); + } + /* + * 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: + kaddr = kmap_atomic(page, KM_USER0); + memset(kaddr + i * blocksize, 0, blocksize); + flush_dcache_page(page); + kunmap_atomic(kaddr, KM_USER0); + 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; + ntfs_inode *ni, *base_ni; + u8 *kaddr; + ntfs_attr_search_ctx *ctx; + MFT_RECORD *mrec; + u32 attr_len; + int err = 0; + + BUG_ON(!PageLocked(page)); + /* + * 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(page->mapping->host); + + /* NInoNonResident() == NInoIndexAllocPresent() */ + if (NInoNonResident(ni)) { + /* + * Only unnamed $DATA attributes can be compressed or + * encrypted. + */ + if (ni->type == AT_DATA && !ni->name_len) { + /* If file is encrypted, deny access, just like NT4. */ + if (NInoEncrypted(ni)) { + err = -EACCES; + goto err_out; + } + /* Compressed data streams are handled in compress.c. */ + if (NInoCompressed(ni)) + return ntfs_read_compressed_block(page); + } + /* Normal 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. We can also do this if the file size is 0. + */ + if (unlikely(page->index > 0 || !i_size_read(VFS_I(ni)))) { + kaddr = kmap_atomic(page, KM_USER0); + memset(kaddr, 0, PAGE_CACHE_SIZE); + flush_dcache_page(page); + kunmap_atomic(kaddr, KM_USER0); + 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; + } + 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); + i_size = i_size_read(VFS_I(ni)); + if (unlikely(attr_len > i_size)) + attr_len = i_size; + kaddr = kmap_atomic(page, KM_USER0); + /* Copy the data to the page. */ + memcpy(kaddr, (u8*)ctx->attr + + le16_to_cpu(ctx->attr->data.resident.value_offset), + attr_len); + /* Zero the remainder of the page. */ + memset(kaddr + attr_len, 0, PAGE_CACHE_SIZE - attr_len); + flush_dcache_page(page); + kunmap_atomic(kaddr, 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; + sector_t block, dblock, iblock; + struct inode *vi; + ntfs_inode *ni; + ntfs_volume *vol; + runlist_element *rl; + struct buffer_head *bh, *head; + 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_bits = vi->i_blkbits; + blocksize = 1 << blocksize_bits; + + if (!page_has_buffers(page)) { + BUG_ON(!PageUptodate(page)); + create_empty_buffers(page, blocksize, + (1 << BH_Uptodate) | (1 << BH_Dirty)); + } + bh = head = page_buffers(page); + if (unlikely(!bh)) { + 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 + * buffer's dirty state as-is. + */ + redirty_page_for_writepage(wbc, page); + unlock_page(page); + return 0; + } + + /* NOTE: Different naming scheme to ntfs_read_block()! */ + + /* The first block in the page. */ + block = (s64)page->index << (PAGE_CACHE_SHIFT - blocksize_bits); + + /* The first out of bounds block for the data size. */ + dblock = (vi->i_size + blocksize - 1) >> blocksize_bits; + + /* The last (fully or partially) initialized block. */ + iblock = ni->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) && + (ni->initialized_size < vi->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) { + // 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; + lcn = err; + } + /* Failed to map the buffer, even after retrying. */ + 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 %lli).", ni->mft_no, + ni->type, (unsigned long long)vcn, + vcn_ofs, is_retry ? " even after " + "retrying" : "", (long long)lcn); + if (!err) + err = -EIO; + 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() isn't 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 { + get_bh(bh); + 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. */ + unlock_page(page); + + /* + * Submit the prepared buffers for i/o. Note the page is unlocked, + * and the async write i/o completion handler can end_page_writeback() + * at any time after the *first* submit_bh(). So the buffers can then + * disappear... + */ + 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; + } + put_bh(bh); + bh = next; + } while (bh != head); + + /* 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 char bh_size_bits = vi->i_blkbits; + unsigned int bh_size = 1 << bh_size_bits; + 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; + int max_bhs = PAGE_CACHE_SIZE / bh_size; + struct buffer_head *bhs[max_bhs]; + runlist_element *rl; + int i, nr_locked_nis, nr_recs, nr_bhs, bhs_per_rec, err, err2; + unsigned rec_size_bits; + BOOL sync, is_mft, page_is_dirty, rec_is_dirty; + + 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))); + BUG_ON(!max_bhs); + + /* Were we called for sync purposes? */ + sync = (wbc->sync_mode == WB_SYNC_ALL); + + /* Make sure we have mapped buffers. */ + BUG_ON(!page_has_buffers(page)); + 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 = (vi->i_size + 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); + 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; + + /* 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; + /* 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).", (s64)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 (unlikely(test_set_buffer_locked(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. */ + down(&tni->extent_lock); + if (tni->nr_extents >= 0) + base_tni = tni; + else { + base_tni = tni->ext.base_ntfs_ino; + BUG_ON(!base_tni); + } + up(&tni->extent_lock); + ntfs_debug("Unlocking %s inode 0x%lx.", + tni == base_tni ? "base" : "extent", + tni->mft_no); + up(&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; + ntfs_inode *ni, *base_ni; + char *kaddr; + ntfs_attr_search_ctx *ctx; + MFT_RECORD *m; + u32 attr_len; + int err; + + 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)) { + /* + * 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; + } + ni = NTFS_I(vi); + + /* NInoNonResident() == NInoIndexAllocPresent() */ + if (NInoNonResident(ni)) { + /* + * Only unnamed $DATA attributes can be compressed, encrypted, + * and/or sparse. + */ + if (ni->type == AT_DATA && !ni->name_len) { + /* If file is encrypted, deny access, just like NT4. */ + if (NInoEncrypted(ni)) { + unlock_page(page); + ntfs_debug("Denying write access to encrypted " + "file."); + return -EACCES; + } + /* Compressed data streams are handled in compress.c. */ + if (NInoCompressed(ni)) { + // TODO: Implement and replace this check 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 (NInoSparse(ni)) { + unlock_page(page); + ntfs_error(vi->i_sb, "Writing to sparse files " + "is not supported yet. Sorry."); + return -EOPNOTSUPP; + } + } + /* 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; + kaddr = kmap_atomic(page, KM_USER0); + memset(kaddr + ofs, 0, PAGE_CACHE_SIZE - ofs); + flush_dcache_page(page); + kunmap_atomic(kaddr, KM_USER0); + } + /* Handle mst protected attributes. */ + if (NInoMstProtected(ni)) + return ntfs_write_mst_block(page, wbc); + /* Normal data stream. */ + return ntfs_write_block(page, wbc); + } + /* + * Attribute is resident, implying it is not compressed, encrypted, + * sparse, 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. + */ + 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; + } + 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); + + /* + * Here, we don't need to zero the out of bounds area everytime because + * the below memcpy() already takes care of the mmap-at-end-of-file + * requirements. If the file is converted to a non-resident one, then + * the code path use is switched to the non-resident one where the + * zeroing happens on each ntfs_writepage() invocation. + * + * The above also applies nicely when i_size is decreased. + * + * When i_size is increased, the memory between the old and new i_size + * _must_ be zeroed (or overwritten with new data). Otherwise we will + * expose data to userspace/disk which should never have been exposed. + * + * FIXME: Ensure that i_size increases do the zeroing/overwriting and + * if we cannot guarantee that, then enable the zeroing below. If the + * zeroing below is enabled, we MUST move the unlock_page() from above + * to after the kunmap_atomic(), i.e. just before the + * end_page_writeback(). + * UPDATE: ntfs_prepare/commit_write() do the zeroing on i_size + * increases for resident attributes so those are ok. + * TODO: ntfs_truncate(), others? + */ + + attr_len = le32_to_cpu(ctx->attr->data.resident.value_length); + i_size = i_size_read(VFS_I(ni)); + kaddr = kmap_atomic(page, KM_USER0); + if (unlikely(attr_len > i_size)) { + /* Zero out of bounds area in the mft record. */ + memset((u8*)ctx->attr + le16_to_cpu( + ctx->attr->data.resident.value_offset) + + i_size, 0, attr_len - i_size); + attr_len = i_size; + } + /* Copy the data from the page to the mft record. */ + memcpy((u8*)ctx->attr + + le16_to_cpu(ctx->attr->data.resident.value_offset), + kaddr, attr_len); + flush_dcache_mft_record_page(ctx->ntfs_ino); + /* Zero out of bounds area in the page cache page. */ + memset(kaddr + attr_len, 0, PAGE_CACHE_SIZE - attr_len); + flush_dcache_page(page); + kunmap_atomic(kaddr, KM_USER0); + + end_page_writeback(page); + + /* 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. Setting page error flag.", err); + SetPageError(page); + } + unlock_page(page); + if (ctx) + ntfs_attr_put_search_ctx(ctx); + if (m) + unmap_mft_record(base_ni); + return err; +} + +/** + * ntfs_prepare_nonresident_write - + * + */ +static int ntfs_prepare_nonresident_write(struct page *page, + unsigned from, unsigned to) +{ + VCN vcn; + LCN lcn; + sector_t block, ablock, iblock; + struct inode *vi; + ntfs_inode *ni; + ntfs_volume *vol; + runlist_element *rl; + struct buffer_head *bh, *head, *wait[2], **wait_bh = wait; + unsigned int vcn_ofs, block_start, block_end, blocksize; + int err; + BOOL is_retry; + 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, from = %u, to = %u.", ni->mft_no, ni->type, + page->index, from, to); + + BUG_ON(!NInoNonResident(ni)); + + blocksize_bits = vi->i_blkbits; + blocksize = 1 << blocksize_bits; + + /* + * create_empty_buffers() will create uptodate/dirty buffers if the + * page is uptodate/dirty. + */ + if (!page_has_buffers(page)) + create_empty_buffers(page, blocksize, 0); + bh = head = page_buffers(page); + if (unlikely(!bh)) + return -ENOMEM; + + /* The first block in the page. */ + block = (s64)page->index << (PAGE_CACHE_SHIFT - blocksize_bits); + + /* + * The first out of bounds block for the allocated size. No need to + * round up as allocated_size is in multiples of cluster size and the + * minimum cluster size is 512 bytes, which is equal to the smallest + * blocksize. + */ + ablock = ni->allocated_size >> blocksize_bits; + + /* The last (fully or partially) initialized block. */ + iblock = ni->initialized_size >> blocksize_bits; + + /* Loop through all the buffers in the page. */ + block_start = 0; + rl = NULL; + err = 0; + do { + block_end = block_start + blocksize; + /* + * If buffer @bh is outside the write, just mark it uptodate + * if the page is uptodate and continue with the next buffer. + */ + if (block_end <= from || block_start >= to) { + if (PageUptodate(page)) { + if (!buffer_uptodate(bh)) + set_buffer_uptodate(bh); + } + continue; + } + /* + * @bh is at least partially being written to. + * Make sure it is not marked as new. + */ + //if (buffer_new(bh)) + // clear_buffer_new(bh); + + if (block >= ablock) { + // TODO: block is above allocated_size, need to + // allocate it. Best done in one go to accommodate not + // only block but all above blocks up to and including: + // ((page->index << PAGE_CACHE_SHIFT) + to + blocksize + // - 1) >> blobksize_bits. Obviously will need to round + // up to next cluster boundary, too. This should be + // done with a helper function, so it can be reused. + ntfs_error(vol->sb, "Writing beyond allocated size " + "is not supported yet. Sorry."); + err = -EOPNOTSUPP; + goto err_out; + // Need to update ablock. + // Need to set_buffer_new() on all block bhs that are + // newly allocated. + } + /* + * Now we have enough allocated size to fulfill the whole + * request, i.e. block < ablock is true. + */ + if (unlikely((block >= iblock) && + (ni->initialized_size < vi->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; + goto err_out; + // 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(). + } + + /* Need to map unmapped buffers. */ + if (!buffer_mapped(bh)) { + /* Unmapped buffer. Need to map it. */ + bh->b_bdev = vol->sb->s_bdev; + + /* Convert block into corresponding vcn and offset. */ + vcn = (VCN)block << blocksize_bits >> + vol->cluster_size_bits; + vcn_ofs = ((VCN)block << blocksize_bits) & + vol->cluster_size_mask; + + 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; + if (unlikely(lcn < 0)) { + /* + * We extended the attribute allocation above. + * If we hit an ENOENT here it means that the + * allocation was insufficient which is a bug. + */ + BUG_ON(lcn == LCN_ENOENT); + + /* It is a hole, need to instantiate it. */ + if (lcn == LCN_HOLE) { + // TODO: Instantiate the hole. + // clear_buffer_new(bh); + // unmap_underlying_metadata(bh->b_bdev, + // bh->b_blocknr); + // For non-uptodate buffers, need to + // zero out the region outside the + // request in this bh or all bhs, + // depending on what we implemented + // above. + // Need to flush_dcache_page(). + // Or could use set_buffer_new() + // instead? + ntfs_error(vol->sb, "Writing into " + "sparse regions is " + "not supported yet. " + "Sorry."); + err = -EOPNOTSUPP; + goto err_out; + } else 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; + lcn = err; + } + /* + * Failed to map the buffer, even after + * retrying. + */ + 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 %lli).", + ni->mft_no, ni->type, + (unsigned long long)vcn, + vcn_ofs, is_retry ? " even " + "after retrying" : "", + (long long)lcn); + if (!err) + err = -EIO; + goto err_out; + } + /* We now have a successful remap, i.e. lcn >= 0. */ + + /* Setup buffer head to correct block. */ + bh->b_blocknr = ((lcn << vol->cluster_size_bits) + + vcn_ofs) >> blocksize_bits; + set_buffer_mapped(bh); + + // FIXME: Something analogous to this is needed for + // each newly allocated block, i.e. BH_New. + // FIXME: Might need to take this out of the + // if (!buffer_mapped(bh)) {}, depending on how we + // implement things during the allocated_size and + // initialized_size extension code above. + if (buffer_new(bh)) { + clear_buffer_new(bh); + unmap_underlying_metadata(bh->b_bdev, + bh->b_blocknr); + if (PageUptodate(page)) { + set_buffer_uptodate(bh); + continue; + } + /* + * Page is _not_ uptodate, zero surrounding + * region. NOTE: This is how we decide if to + * zero or not! + */ + if (block_end > to || block_start < from) { + void *kaddr; + + kaddr = kmap_atomic(page, KM_USER0); + if (block_end > to) + memset(kaddr + to, 0, + block_end - to); + if (block_start < from) + memset(kaddr + block_start, 0, + from - + block_start); + flush_dcache_page(page); + kunmap_atomic(kaddr, KM_USER0); + } + continue; + } + } + /* @bh is mapped, set it uptodate if the page is uptodate. */ + if (PageUptodate(page)) { + if (!buffer_uptodate(bh)) + set_buffer_uptodate(bh); + continue; + } + /* + * The page is not uptodate. The buffer is mapped. If it is not + * uptodate, and it is only partially being written to, we need + * to read the buffer in before the write, i.e. right now. + */ + if (!buffer_uptodate(bh) && + (block_start < from || block_end > to)) { + ll_rw_block(READ, 1, &bh); + *wait_bh++ = bh; + } + } while (block++, block_start = block_end, + (bh = bh->b_this_page) != head); + + /* Release the lock if we took it. */ + if (rl) { + up_read(&ni->runlist.lock); + rl = NULL; + } + + /* If we issued read requests, let them complete. */ + while (wait_bh > wait) { + wait_on_buffer(*--wait_bh); + if (!buffer_uptodate(*wait_bh)) + return -EIO; + } + + ntfs_debug("Done."); + return 0; +err_out: + /* + * Zero out any newly allocated blocks to avoid exposing stale data. + * If BH_New is set, we know that the block was newly allocated in the + * above loop. + * FIXME: What about initialized_size increments? Have we done all the + * required zeroing above? If not this error handling is broken, and + * in particular the if (block_end <= from) check is completely bogus. + */ + bh = head; + block_start = 0; + is_retry = FALSE; + do { + block_end = block_start + blocksize; + if (block_end <= from) + continue; + if (block_start >= to) + break; + if (buffer_new(bh)) { + void *kaddr; + + clear_buffer_new(bh); + kaddr = kmap_atomic(page, KM_USER0); + memset(kaddr + block_start, 0, bh->b_size); + kunmap_atomic(kaddr, KM_USER0); + set_buffer_uptodate(bh); + mark_buffer_dirty(bh); + is_retry = TRUE; + } + } while (block_start = block_end, (bh = bh->b_this_page) != head); + if (is_retry) + flush_dcache_page(page); + if (rl) + up_read(&ni->runlist.lock); + return err; +} + +/** + * ntfs_prepare_write - prepare a page for receiving data + * + * This is called from generic_file_write() with i_sem held on the inode + * (@page->mapping->host). The @page is locked but not kmap()ped. The source + * data has not yet been copied into the @page. + * + * Need to extend the attribute/fill in holes if necessary, create blocks and + * make partially overwritten blocks uptodate, + * + * i_size is not to be modified yet. + * + * Return 0 on success or -errno on error. + * + * Should be using block_prepare_write() [support for sparse files] or + * cont_prepare_write() [no support for sparse files]. Cannot do that due to + * ntfs specifics but can look at them for implementation guidance. + * + * Note: In the range, @from is inclusive and @to is exclusive, i.e. @from is + * the first byte in the page that will be written to and @to is the first byte + * after the last byte that will be written to. + */ +static int ntfs_prepare_write(struct file *file, struct page *page, + unsigned from, unsigned to) +{ + s64 new_size; + struct inode *vi = page->mapping->host; + ntfs_inode *base_ni = NULL, *ni = NTFS_I(vi); + ntfs_volume *vol = ni->vol; + ntfs_attr_search_ctx *ctx = NULL; + MFT_RECORD *m = NULL; + ATTR_RECORD *a; + u8 *kaddr; + u32 attr_len; + int err; + + ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, page index " + "0x%lx, from = %u, to = %u.", vi->i_ino, ni->type, + page->index, from, to); + BUG_ON(!PageLocked(page)); + BUG_ON(from > PAGE_CACHE_SIZE); + BUG_ON(to > PAGE_CACHE_SIZE); + BUG_ON(from > to); + BUG_ON(NInoMstProtected(ni)); + /* + * If a previous ntfs_truncate() failed, repeat it and abort if it + * fails again. + */ + if (unlikely(NInoTruncateFailed(ni))) { + down_write(&vi->i_alloc_sem); + err = ntfs_truncate(vi); + up_write(&vi->i_alloc_sem); + if (err || NInoTruncateFailed(ni)) { + if (!err) + err = -EIO; + goto err_out; + } + } + /* If the attribute is not resident, deal with it elsewhere. */ + if (NInoNonResident(ni)) { + /* + * Only unnamed $DATA attributes can be compressed, encrypted, + * and/or sparse. + */ + if (ni->type == AT_DATA && !ni->name_len) { + /* If file is encrypted, deny access, just like NT4. */ + if (NInoEncrypted(ni)) { + ntfs_debug("Denying write access to encrypted " + "file."); + return -EACCES; + } + /* Compressed data streams are handled in compress.c. */ + if (NInoCompressed(ni)) { + // TODO: Implement and replace this check with + // return ntfs_write_compressed_block(page); + ntfs_error(vi->i_sb, "Writing to compressed " + "files is not supported yet. " + "Sorry."); + return -EOPNOTSUPP; + } + // TODO: Implement and remove this check. + if (NInoSparse(ni)) { + ntfs_error(vi->i_sb, "Writing to sparse files " + "is not supported yet. Sorry."); + return -EOPNOTSUPP; + } + } + /* Normal data stream. */ + return ntfs_prepare_nonresident_write(page, from, to); + } + /* + * Attribute is resident, implying it is not compressed, encrypted, or + * sparse. + */ + BUG_ON(page_has_buffers(page)); + new_size = ((s64)page->index << PAGE_CACHE_SHIFT) + to; + /* If we do not need to resize the attribute allocation we are done. */ + if (new_size <= vi->i_size) + goto done; + + // FIXME: We abort for now as this code is not safe. + ntfs_error(vi->i_sb, "Changing the file size is not supported yet. " + "Sorry."); + return -EOPNOTSUPP; + + /* Map, pin, and lock the (base) mft record. */ + if (!NInoAttr(ni)) + base_ni = ni; + else + base_ni = ni->ext.base_ntfs_ino; + m = map_mft_record(base_ni); + if (IS_ERR(m)) { + err = PTR_ERR(m); + m = NULL; + ctx = NULL; + goto err_out; + } + 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)) { + if (err == -ENOENT) + err = -EIO; + goto err_out; + } + m = ctx->mrec; + a = ctx->attr; + /* The total length of the attribute value. */ + attr_len = le32_to_cpu(a->data.resident.value_length); + BUG_ON(vi->i_size != attr_len); + /* Check if new size is allowed in $AttrDef. */ + err = ntfs_attr_size_bounds_check(vol, ni->type, new_size); + if (unlikely(err)) { + if (err == -ERANGE) { + ntfs_error(vol->sb, "Write would cause the inode " + "0x%lx to exceed the maximum size for " + "its attribute type (0x%x). Aborting " + "write.", vi->i_ino, + le32_to_cpu(ni->type)); + } else { + ntfs_error(vol->sb, "Inode 0x%lx has unknown " + "attribute type 0x%x. Aborting " + "write.", vi->i_ino, + le32_to_cpu(ni->type)); + err = -EIO; + } + goto err_out2; + } + /* + * Extend the attribute record to be able to store the new attribute + * size. + */ + if (new_size >= vol->mft_record_size || ntfs_attr_record_resize(m, a, + le16_to_cpu(a->data.resident.value_offset) + + new_size)) { + /* Not enough space in the mft record. */ + ntfs_error(vol->sb, "Not enough space in the mft record for " + "the resized attribute value. This is not " + "supported yet. Aborting write."); + err = -EOPNOTSUPP; + goto err_out2; + } + /* + * We have enough space in the mft record to fit the write. This + * implies the attribute is smaller than the mft record and hence the + * attribute must be in a single page and hence page->index must be 0. + */ + BUG_ON(page->index); + /* + * If the beginning of the write is past the old size, enlarge the + * attribute value up to the beginning of the write and fill it with + * zeroes. + */ + if (from > attr_len) { + memset((u8*)a + le16_to_cpu(a->data.resident.value_offset) + + attr_len, 0, from - attr_len); + a->data.resident.value_length = cpu_to_le32(from); + /* Zero the corresponding area in the page as well. */ + if (PageUptodate(page)) { + kaddr = kmap_atomic(page, KM_USER0); + memset(kaddr + attr_len, 0, from - attr_len); + kunmap_atomic(kaddr, KM_USER0); + flush_dcache_page(page); + } + } + flush_dcache_mft_record_page(ctx->ntfs_ino); + mark_mft_record_dirty(ctx->ntfs_ino); + ntfs_attr_put_search_ctx(ctx); + unmap_mft_record(base_ni); + /* + * Because resident attributes are handled by memcpy() to/from the + * corresponding MFT record, and because this form of i/o is byte + * aligned rather than block aligned, there is no need to bring the + * page uptodate here as in the non-resident case where we need to + * bring the buffers straddled by the write uptodate before + * generic_file_write() does the copying from userspace. + * + * We thus defer the uptodate bringing of the page region outside the + * region written to to ntfs_commit_write(), which makes the code + * simpler and saves one atomic kmap which is good. + */ +done: + ntfs_debug("Done."); + return 0; +err_out: + if (err == -ENOMEM) + ntfs_warning(vi->i_sb, "Error allocating memory required to " + "prepare the write."); + else { + ntfs_error(vi->i_sb, "Resident attribute prepare write failed " + "with error %i.", err); + NVolSetErrors(vol); + make_bad_inode(vi); + } +err_out2: + if (ctx) + ntfs_attr_put_search_ctx(ctx); + if (m) + unmap_mft_record(base_ni); + return err; +} + +/** + * ntfs_commit_nonresident_write - + * + */ +static int ntfs_commit_nonresident_write(struct page *page, + unsigned from, unsigned to) +{ + s64 pos = ((s64)page->index << PAGE_CACHE_SHIFT) + to; + struct inode *vi = page->mapping->host; + struct buffer_head *bh, *head; + unsigned int block_start, block_end, blocksize; + BOOL partial; + + ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, page index " + "0x%lx, from = %u, to = %u.", vi->i_ino, + NTFS_I(vi)->type, page->index, from, to); + blocksize = 1 << vi->i_blkbits; + + // FIXME: We need a whole slew of special cases in here for compressed + // files for example... + // For now, we know ntfs_prepare_write() would have failed so we can't + // get here in any of the cases which we have to special case, so we + // are just a ripped off, unrolled generic_commit_write(). + + bh = head = page_buffers(page); + block_start = 0; + partial = FALSE; + do { + block_end = block_start + blocksize; + if (block_end <= from || block_start >= to) { + if (!buffer_uptodate(bh)) + partial = TRUE; + } else { + set_buffer_uptodate(bh); + mark_buffer_dirty(bh); + } + } while (block_start = block_end, (bh = bh->b_this_page) != head); + /* + * If this is a partial write which happened to make all buffers + * uptodate then we can optimize away a bogus ->readpage() for the next + * read(). Here we 'discover' whether the page went uptodate as a + * result of this (potentially partial) write. + */ + if (!partial) + SetPageUptodate(page); + /* + * Not convinced about this at all. See disparity comment above. For + * now we know ntfs_prepare_write() would have failed in the write + * exceeds i_size case, so this will never trigger which is fine. + */ + if (pos > vi->i_size) { + ntfs_error(vi->i_sb, "Writing beyond the existing file size is " + "not supported yet. Sorry."); + return -EOPNOTSUPP; + // vi->i_size = pos; + // mark_inode_dirty(vi); + } + ntfs_debug("Done."); + return 0; +} + +/** + * ntfs_commit_write - commit the received data + * + * This is called from generic_file_write() with i_sem held on the inode + * (@page->mapping->host). The @page is locked but not kmap()ped. The source + * data has already been copied into the @page. ntfs_prepare_write() has been + * called before the data copied and it returned success so we can take the + * results of various BUG checks and some error handling for granted. + * + * Need to mark modified blocks dirty so they get written out later when + * ntfs_writepage() is invoked by the VM. + * + * Return 0 on success or -errno on error. + * + * Should be using generic_commit_write(). This marks buffers uptodate and + * dirty, sets the page uptodate if all buffers in the page are uptodate, and + * updates i_size if the end of io is beyond i_size. In that case, it also + * marks the inode dirty. + * + * Cannot use generic_commit_write() due to ntfs specialities but can look at + * it for implementation guidance. + * + * If things have gone as outlined in ntfs_prepare_write(), then we do not + * need to do any page content modifications here at all, except in the write + * to resident attribute case, where we need to do the uptodate bringing here + * which we combine with the copying into the mft record which means we save + * one atomic kmap. + */ +static int ntfs_commit_write(struct file *file, struct page *page, + unsigned from, unsigned to) +{ + struct inode *vi = page->mapping->host; + ntfs_inode *base_ni, *ni = NTFS_I(vi); + char *kaddr, *kattr; + ntfs_attr_search_ctx *ctx; + MFT_RECORD *m; + ATTR_RECORD *a; + u32 attr_len; + int err; + + ntfs_debug("Entering for inode 0x%lx, attribute type 0x%x, page index " + "0x%lx, from = %u, to = %u.", vi->i_ino, ni->type, + page->index, from, to); + /* If the attribute is not resident, deal with it elsewhere. */ + if (NInoNonResident(ni)) { + /* Only unnamed $DATA attributes can be compressed/encrypted. */ + if (ni->type == AT_DATA && !ni->name_len) { + /* Encrypted files need separate handling. */ + if (NInoEncrypted(ni)) { + // We never get here at present! + BUG(); + } + /* Compressed data streams are handled in compress.c. */ + if (NInoCompressed(ni)) { + // TODO: Implement this! + // return ntfs_write_compressed_block(page); + // We never get here at present! + BUG(); + } + } + /* Normal data stream. */ + return ntfs_commit_nonresident_write(page, from, to); + } + /* + * Attribute is resident, implying it is not compressed, encrypted, or + * sparse. + */ + 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; + } + 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)) { + if (err == -ENOENT) + err = -EIO; + goto err_out; + } + a = ctx->attr; + /* The total length of the attribute value. */ + attr_len = le32_to_cpu(a->data.resident.value_length); + BUG_ON(from > attr_len); + kattr = (u8*)a + le16_to_cpu(a->data.resident.value_offset); + kaddr = kmap_atomic(page, KM_USER0); + /* Copy the received data from the page to the mft record. */ + memcpy(kattr + from, kaddr + from, to - from); + /* Update the attribute length if necessary. */ + if (to > attr_len) { + attr_len = to; + a->data.resident.value_length = cpu_to_le32(attr_len); + } + /* + * If the page is not uptodate, bring the out of bounds area(s) + * uptodate by copying data from the mft record to the page. + */ + if (!PageUptodate(page)) { + if (from > 0) + memcpy(kaddr, kattr, from); + if (to < attr_len) + memcpy(kaddr + to, kattr + to, attr_len - to); + /* Zero the region outside the end of the attribute value. */ + if (attr_len < PAGE_CACHE_SIZE) + memset(kaddr + attr_len, 0, PAGE_CACHE_SIZE - attr_len); + /* + * The probability of not having done any of the above is + * extremely small, so we just flush unconditionally. + */ + flush_dcache_page(page); + SetPageUptodate(page); + } + kunmap_atomic(kaddr, KM_USER0); + /* Update i_size if necessary. */ + if (vi->i_size < attr_len) { + ni->allocated_size = ni->initialized_size = attr_len; + i_size_write(vi, attr_len); + } + /* Mark the mft record dirty, so it gets written back. */ + flush_dcache_mft_record_page(ctx->ntfs_ino); + mark_mft_record_dirty(ctx->ntfs_ino); + ntfs_attr_put_search_ctx(ctx); + unmap_mft_record(base_ni); + ntfs_debug("Done."); + return 0; +err_out: + if (err == -ENOMEM) { + ntfs_warning(vi->i_sb, "Error allocating memory required to " + "commit the write."); + if (PageUptodate(page)) { + ntfs_warning(vi->i_sb, "Page is uptodate, setting " + "dirty so the write will be retried " + "later on by the VM."); + /* + * Put the page on mapping->dirty_pages, but leave its + * buffers' dirty state as-is. + */ + __set_page_dirty_nobuffers(page); + err = 0; + } else + ntfs_error(vi->i_sb, "Page is not uptodate. Written " + "data has been lost."); + } else { + ntfs_error(vi->i_sb, "Resident attribute commit write failed " + "with error %i.", err); + NVolSetErrors(ni->vol); + make_bad_inode(vi); + } + 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 + */ +struct address_space_operations ntfs_aops = { + .readpage = ntfs_readpage, /* Fill page with data. */ + .sync_page = block_sync_page, /* Currently, just unplugs the + disk request queue. */ +#ifdef NTFS_RW + .writepage = ntfs_writepage, /* Write dirty page to disk. */ + .prepare_write = ntfs_prepare_write, /* Prepare page and buffers + ready to receive data. */ + .commit_write = ntfs_commit_write, /* Commit received data. */ +#endif /* NTFS_RW */ +}; + +/** + * ntfs_mst_aops - general address space operations for mst protecteed inodes + * and attributes + */ +struct address_space_operations ntfs_mst_aops = { + .readpage = ntfs_readpage, /* Fill page with data. */ + .sync_page = block_sync_page, /* Currently, just unplugs the + disk request queue. */ +#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 */ +}; + +#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 = 1 << VFS_I(ni)->i_blkbits; + 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); + 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 */ |