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Diffstat (limited to 'fs/ntfs/mft.c')
| -rw-r--r-- | fs/ntfs/mft.c | 2829 |
1 files changed, 2829 insertions, 0 deletions
diff --git a/fs/ntfs/mft.c b/fs/ntfs/mft.c new file mode 100644 index 00000000000..dfa85ac2f8b --- /dev/null +++ b/fs/ntfs/mft.c @@ -0,0 +1,2829 @@ +/** + * mft.c - NTFS kernel mft record operations. 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/buffer_head.h> +#include <linux/swap.h> + +#include "attrib.h" +#include "aops.h" +#include "bitmap.h" +#include "debug.h" +#include "dir.h" +#include "lcnalloc.h" +#include "malloc.h" +#include "mft.h" +#include "ntfs.h" + +/** + * map_mft_record_page - map the page in which a specific mft record resides + * @ni: ntfs inode whose mft record page to map + * + * This maps the page in which the mft record of the ntfs inode @ni is situated + * and returns a pointer to the mft record within the mapped page. + * + * Return value needs to be checked with IS_ERR() and if that is true PTR_ERR() + * contains the negative error code returned. + */ +static inline MFT_RECORD *map_mft_record_page(ntfs_inode *ni) +{ + ntfs_volume *vol = ni->vol; + struct inode *mft_vi = vol->mft_ino; + struct page *page; + unsigned long index, ofs, end_index; + + BUG_ON(ni->page); + /* + * The index into the page cache and the offset within the page cache + * page of the wanted mft record. FIXME: We need to check for + * overflowing the unsigned long, but I don't think we would ever get + * here if the volume was that big... + */ + index = ni->mft_no << vol->mft_record_size_bits >> PAGE_CACHE_SHIFT; + ofs = (ni->mft_no << vol->mft_record_size_bits) & ~PAGE_CACHE_MASK; + + /* The maximum valid index into the page cache for $MFT's data. */ + end_index = mft_vi->i_size >> PAGE_CACHE_SHIFT; + + /* If the wanted index is out of bounds the mft record doesn't exist. */ + if (unlikely(index >= end_index)) { + if (index > end_index || (mft_vi->i_size & ~PAGE_CACHE_MASK) < + ofs + vol->mft_record_size) { + page = ERR_PTR(-ENOENT); + ntfs_error(vol->sb, "Attemt to read mft record 0x%lx, " + "which is beyond the end of the mft. " + "This is probably a bug in the ntfs " + "driver.", ni->mft_no); + goto err_out; + } + } + /* Read, map, and pin the page. */ + page = ntfs_map_page(mft_vi->i_mapping, index); + if (likely(!IS_ERR(page))) { + /* Catch multi sector transfer fixup errors. */ + if (likely(ntfs_is_mft_recordp((le32*)(page_address(page) + + ofs)))) { + ni->page = page; + ni->page_ofs = ofs; + return page_address(page) + ofs; + } + ntfs_error(vol->sb, "Mft record 0x%lx is corrupt. " + "Run chkdsk.", ni->mft_no); + ntfs_unmap_page(page); + page = ERR_PTR(-EIO); + } +err_out: + ni->page = NULL; + ni->page_ofs = 0; + return (void*)page; +} + +/** + * map_mft_record - map, pin and lock an mft record + * @ni: ntfs inode whose MFT record to map + * + * First, take the mrec_lock semaphore. We might now be sleeping, while waiting + * for the semaphore if it was already locked by someone else. + * + * The page of the record is mapped using map_mft_record_page() before being + * returned to the caller. + * + * This in turn uses ntfs_map_page() to get the page containing the wanted mft + * record (it in turn calls read_cache_page() which reads it in from disk if + * necessary, increments the use count on the page so that it cannot disappear + * under us and returns a reference to the page cache page). + * + * If read_cache_page() invokes ntfs_readpage() to load the page from disk, it + * sets PG_locked and clears PG_uptodate on the page. Once I/O has completed + * and the post-read mst fixups on each mft record in the page have been + * performed, the page gets PG_uptodate set and PG_locked cleared (this is done + * in our asynchronous I/O completion handler end_buffer_read_mft_async()). + * ntfs_map_page() waits for PG_locked to become clear and checks if + * PG_uptodate is set and returns an error code if not. This provides + * sufficient protection against races when reading/using the page. + * + * However there is the write mapping to think about. Doing the above described + * checking here will be fine, because when initiating the write we will set + * PG_locked and clear PG_uptodate making sure nobody is touching the page + * contents. Doing the locking this way means that the commit to disk code in + * the page cache code paths is automatically sufficiently locked with us as + * we will not touch a page that has been locked or is not uptodate. The only + * locking problem then is them locking the page while we are accessing it. + * + * So that code will end up having to own the mrec_lock of all mft + * records/inodes present in the page before I/O can proceed. In that case we + * wouldn't need to bother with PG_locked and PG_uptodate as nobody will be + * accessing anything without owning the mrec_lock semaphore. But we do need + * to use them because of the read_cache_page() invocation and the code becomes + * so much simpler this way that it is well worth it. + * + * The mft record is now ours and we return a pointer to it. You need to check + * the returned pointer with IS_ERR() and if that is true, PTR_ERR() will return + * the error code. + * + * NOTE: Caller is responsible for setting the mft record dirty before calling + * unmap_mft_record(). This is obviously only necessary if the caller really + * modified the mft record... + * Q: Do we want to recycle one of the VFS inode state bits instead? + * A: No, the inode ones mean we want to change the mft record, not we want to + * write it out. + */ +MFT_RECORD *map_mft_record(ntfs_inode *ni) +{ + MFT_RECORD *m; + + ntfs_debug("Entering for mft_no 0x%lx.", ni->mft_no); + + /* Make sure the ntfs inode doesn't go away. */ + atomic_inc(&ni->count); + + /* Serialize access to this mft record. */ + down(&ni->mrec_lock); + + m = map_mft_record_page(ni); + if (likely(!IS_ERR(m))) + return m; + + up(&ni->mrec_lock); + atomic_dec(&ni->count); + ntfs_error(ni->vol->sb, "Failed with error code %lu.", -PTR_ERR(m)); + return m; +} + +/** + * unmap_mft_record_page - unmap the page in which a specific mft record resides + * @ni: ntfs inode whose mft record page to unmap + * + * This unmaps the page in which the mft record of the ntfs inode @ni is + * situated and returns. This is a NOOP if highmem is not configured. + * + * The unmap happens via ntfs_unmap_page() which in turn decrements the use + * count on the page thus releasing it from the pinned state. + * + * We do not actually unmap the page from memory of course, as that will be + * done by the page cache code itself when memory pressure increases or + * whatever. + */ +static inline void unmap_mft_record_page(ntfs_inode *ni) +{ + BUG_ON(!ni->page); + + // TODO: If dirty, blah... + ntfs_unmap_page(ni->page); + ni->page = NULL; + ni->page_ofs = 0; + return; +} + +/** + * unmap_mft_record - release a mapped mft record + * @ni: ntfs inode whose MFT record to unmap + * + * We release the page mapping and the mrec_lock mutex which unmaps the mft + * record and releases it for others to get hold of. We also release the ntfs + * inode by decrementing the ntfs inode reference count. + * + * NOTE: If caller has modified the mft record, it is imperative to set the mft + * record dirty BEFORE calling unmap_mft_record(). + */ +void unmap_mft_record(ntfs_inode *ni) +{ + struct page *page = ni->page; + + BUG_ON(!page); + + ntfs_debug("Entering for mft_no 0x%lx.", ni->mft_no); + + unmap_mft_record_page(ni); + up(&ni->mrec_lock); + atomic_dec(&ni->count); + /* + * If pure ntfs_inode, i.e. no vfs inode attached, we leave it to + * ntfs_clear_extent_inode() in the extent inode case, and to the + * caller in the non-extent, yet pure ntfs inode case, to do the actual + * tear down of all structures and freeing of all allocated memory. + */ + return; +} + +/** + * map_extent_mft_record - load an extent inode and attach it to its base + * @base_ni: base ntfs inode + * @mref: mft reference of the extent inode to load + * @ntfs_ino: on successful return, pointer to the ntfs_inode structure + * + * Load the extent mft record @mref and attach it to its base inode @base_ni. + * Return the mapped extent mft record if IS_ERR(result) is false. Otherwise + * PTR_ERR(result) gives the negative error code. + * + * On successful return, @ntfs_ino contains a pointer to the ntfs_inode + * structure of the mapped extent inode. + */ +MFT_RECORD *map_extent_mft_record(ntfs_inode *base_ni, MFT_REF mref, + ntfs_inode **ntfs_ino) +{ + MFT_RECORD *m; + ntfs_inode *ni = NULL; + ntfs_inode **extent_nis = NULL; + int i; + unsigned long mft_no = MREF(mref); + u16 seq_no = MSEQNO(mref); + BOOL destroy_ni = FALSE; + + ntfs_debug("Mapping extent mft record 0x%lx (base mft record 0x%lx).", + mft_no, base_ni->mft_no); + /* Make sure the base ntfs inode doesn't go away. */ + atomic_inc(&base_ni->count); + /* + * Check if this extent inode has already been added to the base inode, + * in which case just return it. If not found, add it to the base + * inode before returning it. + */ + down(&base_ni->extent_lock); + if (base_ni->nr_extents > 0) { + extent_nis = base_ni->ext.extent_ntfs_inos; + for (i = 0; i < base_ni->nr_extents; i++) { + if (mft_no != extent_nis[i]->mft_no) + continue; + ni = extent_nis[i]; + /* Make sure the ntfs inode doesn't go away. */ + atomic_inc(&ni->count); + break; + } + } + if (likely(ni != NULL)) { + up(&base_ni->extent_lock); + atomic_dec(&base_ni->count); + /* We found the record; just have to map and return it. */ + m = map_mft_record(ni); + /* map_mft_record() has incremented this on success. */ + atomic_dec(&ni->count); + if (likely(!IS_ERR(m))) { + /* Verify the sequence number. */ + if (likely(le16_to_cpu(m->sequence_number) == seq_no)) { + ntfs_debug("Done 1."); + *ntfs_ino = ni; + return m; + } + unmap_mft_record(ni); + ntfs_error(base_ni->vol->sb, "Found stale extent mft " + "reference! Corrupt file system. " + "Run chkdsk."); + return ERR_PTR(-EIO); + } +map_err_out: + ntfs_error(base_ni->vol->sb, "Failed to map extent " + "mft record, error code %ld.", -PTR_ERR(m)); + return m; + } + /* Record wasn't there. Get a new ntfs inode and initialize it. */ + ni = ntfs_new_extent_inode(base_ni->vol->sb, mft_no); + if (unlikely(!ni)) { + up(&base_ni->extent_lock); + atomic_dec(&base_ni->count); + return ERR_PTR(-ENOMEM); + } + ni->vol = base_ni->vol; + ni->seq_no = seq_no; + ni->nr_extents = -1; + ni->ext.base_ntfs_ino = base_ni; + /* Now map the record. */ + m = map_mft_record(ni); + if (IS_ERR(m)) { + up(&base_ni->extent_lock); + atomic_dec(&base_ni->count); + ntfs_clear_extent_inode(ni); + goto map_err_out; + } + /* Verify the sequence number if it is present. */ + if (seq_no && (le16_to_cpu(m->sequence_number) != seq_no)) { + ntfs_error(base_ni->vol->sb, "Found stale extent mft " + "reference! Corrupt file system. Run chkdsk."); + destroy_ni = TRUE; + m = ERR_PTR(-EIO); + goto unm_err_out; + } + /* Attach extent inode to base inode, reallocating memory if needed. */ + if (!(base_ni->nr_extents & 3)) { + ntfs_inode **tmp; + int new_size = (base_ni->nr_extents + 4) * sizeof(ntfs_inode *); + + tmp = (ntfs_inode **)kmalloc(new_size, GFP_NOFS); + if (unlikely(!tmp)) { + ntfs_error(base_ni->vol->sb, "Failed to allocate " + "internal buffer."); + destroy_ni = TRUE; + m = ERR_PTR(-ENOMEM); + goto unm_err_out; + } + if (base_ni->nr_extents) { + BUG_ON(!base_ni->ext.extent_ntfs_inos); + memcpy(tmp, base_ni->ext.extent_ntfs_inos, new_size - + 4 * sizeof(ntfs_inode *)); + kfree(base_ni->ext.extent_ntfs_inos); + } + base_ni->ext.extent_ntfs_inos = tmp; + } + base_ni->ext.extent_ntfs_inos[base_ni->nr_extents++] = ni; + up(&base_ni->extent_lock); + atomic_dec(&base_ni->count); + ntfs_debug("Done 2."); + *ntfs_ino = ni; + return m; +unm_err_out: + unmap_mft_record(ni); + up(&base_ni->extent_lock); + atomic_dec(&base_ni->count); + /* + * If the extent inode was not attached to the base inode we need to + * release it or we will leak memory. + */ + if (destroy_ni) + ntfs_clear_extent_inode(ni); + return m; +} + +#ifdef NTFS_RW + +/** + * __mark_mft_record_dirty - set the mft record and the page containing it dirty + * @ni: ntfs inode describing the mapped mft record + * + * Internal function. Users should call mark_mft_record_dirty() instead. + * + * Set the mapped (extent) mft record of the (base or extent) ntfs inode @ni, + * as well as the page containing the mft record, dirty. Also, mark the base + * vfs inode dirty. This ensures that any changes to the mft record are + * written out to disk. + * + * NOTE: We only set I_DIRTY_SYNC and I_DIRTY_DATASYNC (and not I_DIRTY_PAGES) + * on the base vfs inode, because even though file data may have been modified, + * it is dirty in the inode meta data rather than the data page cache of the + * inode, and thus there are no data pages that need writing out. Therefore, a + * full mark_inode_dirty() is overkill. A mark_inode_dirty_sync(), on the + * other hand, is not sufficient, because I_DIRTY_DATASYNC needs to be set to + * ensure ->write_inode is called from generic_osync_inode() and this needs to + * happen or the file data would not necessarily hit the device synchronously, + * even though the vfs inode has the O_SYNC flag set. Also, I_DIRTY_DATASYNC + * simply "feels" better than just I_DIRTY_SYNC, since the file data has not + * actually hit the block device yet, which is not what I_DIRTY_SYNC on its own + * would suggest. + */ +void __mark_mft_record_dirty(ntfs_inode *ni) +{ + ntfs_inode *base_ni; + + ntfs_debug("Entering for inode 0x%lx.", ni->mft_no); + BUG_ON(NInoAttr(ni)); + mark_ntfs_record_dirty(ni->page, ni->page_ofs); + /* Determine the base vfs inode and mark it dirty, too. */ + down(&ni->extent_lock); + if (likely(ni->nr_extents >= 0)) + base_ni = ni; + else + base_ni = ni->ext.base_ntfs_ino; + up(&ni->extent_lock); + __mark_inode_dirty(VFS_I(base_ni), I_DIRTY_SYNC | I_DIRTY_DATASYNC); +} + +static const char *ntfs_please_email = "Please email " + "linux-ntfs-dev@lists.sourceforge.net and say that you saw " + "this message. Thank you."; + +/** + * ntfs_sync_mft_mirror_umount - synchronise an mft record to the mft mirror + * @vol: ntfs volume on which the mft record to synchronize resides + * @mft_no: mft record number of mft record to synchronize + * @m: mapped, mst protected (extent) mft record to synchronize + * + * Write the mapped, mst protected (extent) mft record @m with mft record + * number @mft_no to the mft mirror ($MFTMirr) of the ntfs volume @vol, + * bypassing the page cache and the $MFTMirr inode itself. + * + * This function is only for use at umount time when the mft mirror inode has + * already been disposed off. We BUG() if we are called while the mft mirror + * inode is still attached to the volume. + * + * On success return 0. On error return -errno. + * + * NOTE: This function is not implemented yet as I am not convinced it can + * actually be triggered considering the sequence of commits we do in super.c:: + * ntfs_put_super(). But just in case we provide this place holder as the + * alternative would be either to BUG() or to get a NULL pointer dereference + * and Oops. + */ +static int ntfs_sync_mft_mirror_umount(ntfs_volume *vol, + const unsigned long mft_no, MFT_RECORD *m) +{ + BUG_ON(vol->mftmirr_ino); + ntfs_error(vol->sb, "Umount time mft mirror syncing is not " + "implemented yet. %s", ntfs_please_email); + return -EOPNOTSUPP; +} + +/** + * ntfs_sync_mft_mirror - synchronize an mft record to the mft mirror + * @vol: ntfs volume on which the mft record to synchronize resides + * @mft_no: mft record number of mft record to synchronize + * @m: mapped, mst protected (extent) mft record to synchronize + * @sync: if true, wait for i/o completion + * + * Write the mapped, mst protected (extent) mft record @m with mft record + * number @mft_no to the mft mirror ($MFTMirr) of the ntfs volume @vol. + * + * On success return 0. On error return -errno and set the volume errors flag + * in the ntfs volume @vol. + * + * NOTE: We always perform synchronous i/o and ignore the @sync parameter. + * + * TODO: If @sync is false, want to do truly asynchronous i/o, i.e. just + * schedule i/o via ->writepage or do it via kntfsd or whatever. + */ +int ntfs_sync_mft_mirror(ntfs_volume *vol, const unsigned long mft_no, + MFT_RECORD *m, int sync) +{ + struct page *page; + unsigned int blocksize = vol->sb->s_blocksize; + int max_bhs = vol->mft_record_size / blocksize; + struct buffer_head *bhs[max_bhs]; + struct buffer_head *bh, *head; + u8 *kmirr; + runlist_element *rl; + unsigned int block_start, block_end, m_start, m_end, page_ofs; + int i_bhs, nr_bhs, err = 0; + unsigned char blocksize_bits = vol->mftmirr_ino->i_blkbits; + + ntfs_debug("Entering for inode 0x%lx.", mft_no); + BUG_ON(!max_bhs); + if (unlikely(!vol->mftmirr_ino)) { + /* This could happen during umount... */ + err = ntfs_sync_mft_mirror_umount(vol, mft_no, m); + if (likely(!err)) + return err; + goto err_out; + } + /* Get the page containing the mirror copy of the mft record @m. */ + page = ntfs_map_page(vol->mftmirr_ino->i_mapping, mft_no >> + (PAGE_CACHE_SHIFT - vol->mft_record_size_bits)); + if (IS_ERR(page)) { + ntfs_error(vol->sb, "Failed to map mft mirror page."); + err = PTR_ERR(page); + goto err_out; + } + lock_page(page); + BUG_ON(!PageUptodate(page)); + ClearPageUptodate(page); + /* Offset of the mft mirror record inside the page. */ + page_ofs = (mft_no << vol->mft_record_size_bits) & ~PAGE_CACHE_MASK; + /* The address in the page of the mirror copy of the mft record @m. */ + kmirr = page_address(page) + page_ofs; + /* Copy the mst protected mft record to the mirror. */ + memcpy(kmirr, m, vol->mft_record_size); + /* Create uptodate buffers if not present. */ + if (unlikely(!page_has_buffers(page))) { + struct buffer_head *tail; + + bh = head = alloc_page_buffers(page, blocksize, 1); + do { + set_buffer_uptodate(bh); + tail = bh; + bh = bh->b_this_page; + } while (bh); + tail->b_this_page = head; + attach_page_buffers(page, head); + BUG_ON(!page_has_buffers(page)); + } + bh = head = page_buffers(page); + BUG_ON(!bh); + rl = NULL; + nr_bhs = 0; + block_start = 0; + m_start = kmirr - (u8*)page_address(page); + m_end = m_start + vol->mft_record_size; + do { + block_end = block_start + blocksize; + /* If the buffer is outside the mft record, skip it. */ + if (block_end <= m_start) + continue; + if (unlikely(block_start >= m_end)) + break; + /* 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)mft_no << vol->mft_record_size_bits) + + (block_start - m_start); + vcn_ofs = vcn & vol->cluster_size_mask; + vcn >>= vol->cluster_size_bits; + if (!rl) { + down_read(&NTFS_I(vol->mftmirr_ino)-> + runlist.lock); + rl = NTFS_I(vol->mftmirr_ino)->runlist.rl; + /* + * $MFTMirr always has the whole of its runlist + * in memory. + */ + BUG_ON(!rl); + } + /* Seek to element containing target vcn. */ + while (rl->length && rl[1].vcn <= vcn) + rl++; + lcn = ntfs_rl_vcn_to_lcn(rl, vcn); + /* For $MFTMirr, only lcn >= 0 is a successful remap. */ + if (likely(lcn >= 0)) { + /* Setup buffer head to correct block. */ + bh->b_blocknr = ((lcn << + vol->cluster_size_bits) + + vcn_ofs) >> blocksize_bits; + set_buffer_mapped(bh); + } else { + bh->b_blocknr = -1; + ntfs_error(vol->sb, "Cannot write mft mirror " + "record 0x%lx because its " + "location on disk could not " + "be determined (error code " + "%lli).", mft_no, + (long long)lcn); + err = -EIO; + } + } + BUG_ON(!buffer_uptodate(bh)); + BUG_ON(!nr_bhs && (m_start != block_start)); + BUG_ON(nr_bhs >= max_bhs); + bhs[nr_bhs++] = bh; + BUG_ON((nr_bhs >= max_bhs) && (m_end != block_end)); + } while (block_start = block_end, (bh = bh->b_this_page) != head); + if (unlikely(rl)) + up_read(&NTFS_I(vol->mftmirr_ino)->runlist.lock); + if (likely(!err)) { + /* Lock buffers and start synchronous write i/o on them. */ + for (i_bhs = 0; i_bhs < nr_bhs; i_bhs++) { + struct buffer_head *tbh = bhs[i_bhs]; + + if (unlikely(test_set_buffer_locked(tbh))) + BUG(); + BUG_ON(!buffer_uptodate(tbh)); + clear_buffer_dirty(tbh); + get_bh(tbh); + tbh->b_end_io = end_buffer_write_sync; + submit_bh(WRITE, tbh); + } + /* Wait on i/o completion of buffers. */ + for (i_bhs = 0; i_bhs < nr_bhs; i_bhs++) { + struct buffer_head *tbh = bhs[i_bhs]; + + wait_on_buffer(tbh); + if (unlikely(!buffer_uptodate(tbh))) { + err = -EIO; + /* + * Set the buffer uptodate so the page and + * buffer states do not become out of sync. + */ + set_buffer_uptodate(tbh); + } + } + } else /* if (unlikely(err)) */ { + /* Clean the buffers. */ + for (i_bhs = 0; i_bhs < nr_bhs; i_bhs++) + clear_buffer_dirty(bhs[i_bhs]); + } + /* Current state: all buffers are clean, unlocked, and uptodate. */ + /* Remove the mst protection fixups again. */ + post_write_mst_fixup((NTFS_RECORD*)kmirr); + flush_dcache_page(page); + SetPageUptodate(page); + unlock_page(page); + ntfs_unmap_page(page); + if (likely(!err)) { + ntfs_debug("Done."); + } else { + ntfs_error(vol->sb, "I/O error while writing mft mirror " + "record 0x%lx!", mft_no); +err_out: + ntfs_error(vol->sb, "Failed to synchronize $MFTMirr (error " + "code %i). Volume will be left marked dirty " + "on umount. Run ntfsfix on the partition " + "after umounting to correct this.", -err); + NVolSetErrors(vol); + } + return err; +} + +/** + * write_mft_record_nolock - write out a mapped (extent) mft record + * @ni: ntfs inode describing the mapped (extent) mft record + * @m: mapped (extent) mft record to write + * @sync: if true, wait for i/o completion + * + * Write the mapped (extent) mft record @m described by the (regular or extent) + * ntfs inode @ni to backing store. If the mft record @m has a counterpart in + * the mft mirror, that is also updated. + * + * We only write the mft record if the ntfs inode @ni is dirty and the first + * buffer belonging to its mft record is dirty, too. We ignore the dirty state + * of subsequent buffers because we could have raced with + * fs/ntfs/aops.c::mark_ntfs_record_dirty(). + * + * On success, clean the mft record and return 0. On error, leave the mft + * record dirty and return -errno. The caller should call make_bad_inode() on + * the base inode to ensure no more access happens to this inode. We do not do + * it here as the caller may want to finish writing other extent mft records + * first to minimize on-disk metadata inconsistencies. + * + * NOTE: We always perform synchronous i/o and ignore the @sync parameter. + * However, if the mft record has a counterpart in the mft mirror and @sync is + * true, we write the mft record, wait for i/o completion, and only then write + * the mft mirror copy. This ensures that if the system crashes either the mft + * or the mft mirror will contain a self-consistent mft record @m. If @sync is + * false on the other hand, we start i/o on both and then wait for completion + * on them. This provides a speedup but no longer guarantees that you will end + * up with a self-consistent mft record in the case of a crash but if you asked + * for asynchronous writing you probably do not care about that anyway. + * + * TODO: If @sync is false, want to do truly asynchronous i/o, i.e. just + * schedule i/o via ->writepage or do it via kntfsd or whatever. + */ +int write_mft_record_nolock(ntfs_inode *ni, MFT_RECORD *m, int sync) +{ + ntfs_volume *vol = ni->vol; + struct page *page = ni->page; + unsigned char blocksize_bits = vol->mft_ino->i_blkbits; + unsigned int blocksize = 1 << blocksize_bits; + int max_bhs = vol->mft_record_size / blocksize; + struct buffer_head *bhs[max_bhs]; + struct buffer_head *bh, *head; + runlist_element *rl; + unsigned int block_start, block_end, m_start, m_end; + int i_bhs, nr_bhs, err = 0; + + ntfs_debug("Entering for inode 0x%lx.", ni->mft_no); + BUG_ON(NInoAttr(ni)); + BUG_ON(!max_bhs); + BUG_ON(!PageLocked(page)); + /* + * If the ntfs_inode is clean no need to do anything. If it is dirty, + * mark it as clean now so that it can be redirtied later on if needed. + * There is no danger of races since the caller is holding the locks + * for the mft record @m and the page it is in. + */ + if (!NInoTestClearDirty(ni)) + goto done; + BUG_ON(!page_has_buffers(page)); + bh = head = page_buffers(page); + BUG_ON(!bh); + rl = NULL; + nr_bhs = 0; + block_start = 0; + m_start = ni->page_ofs; + m_end = m_start + vol->mft_record_size; + do { + block_end = block_start + blocksize; + /* If the buffer is outside the mft record, skip it. */ + if (block_end <= m_start) + continue; + if (unlikely(block_start >= m_end)) + break; + /* + * If 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 (block_start == m_start) { + /* This block is the first one in the record. */ + if (!buffer_dirty(bh)) { + BUG_ON(nr_bhs); + /* Clean records are not written out. */ + break; + } + } + /* 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)ni->mft_no << vol->mft_record_size_bits) + + (block_start - m_start); + vcn_ofs = vcn & vol->cluster_size_mask; + vcn >>= vol->cluster_size_bits; + if (!rl) { + down_read(&NTFS_I(vol->mft_ino)->runlist.lock); + rl = NTFS_I(vol->mft_ino)->runlist.rl; + BUG_ON(!rl); + } + /* Seek to element containing target vcn. */ + while (rl->length && rl[1].vcn <= vcn) + rl++; + lcn = ntfs_rl_vcn_to_lcn(rl, vcn); + /* For $MFT, only lcn >= 0 is a successful remap. */ + if (likely(lcn >= 0)) { + /* Setup buffer head to correct block. */ + bh->b_blocknr = ((lcn << + vol->cluster_size_bits) + + vcn_ofs) >> blocksize_bits; + set_buffer_mapped(bh); + } else { + bh->b_blocknr = -1; + ntfs_error(vol->sb, "Cannot write mft record " + "0x%lx because its location " + "on disk could not be " + "determined (error code %lli).", + ni->mft_no, (long long)lcn); + err = -EIO; + } + } + BUG_ON(!buffer_uptodate(bh)); + BUG_ON(!nr_bhs && (m_start != block_start)); + BUG_ON(nr_bhs >= max_bhs); + bhs[nr_bhs++] = bh; + BUG_ON((nr_bhs >= max_bhs) && (m_end != block_end)); + } while (block_start = block_end, (bh = bh->b_this_page) != head); + if (unlikely(rl)) + up_read(&NTFS_I(vol->mft_ino)->runlist.lock); + if (!nr_bhs) + goto done; + if (unlikely(err)) + goto cleanup_out; + /* Apply the mst protection fixups. */ + err = pre_write_mst_fixup((NTFS_RECORD*)m, vol->mft_record_size); + if (err) { + ntfs_error(vol->sb, "Failed to apply mst fixups!"); + goto cleanup_out; + } + flush_dcache_mft_record_page(ni); + /* Lock buffers and start synchronous write i/o on them. */ + for (i_bhs = 0; i_bhs < nr_bhs; i_bhs++) { + struct buffer_head *tbh = bhs[i_bhs]; + + if (unlikely(test_set_buffer_locked(tbh))) + BUG(); + BUG_ON(!buffer_uptodate(tbh)); + clear_buffer_dirty(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 (!sync && ni->mft_no < vol->mftmirr_size) + ntfs_sync_mft_mirror(vol, ni->mft_no, m, sync); + /* Wait on i/o completion of buffers. */ + for (i_bhs = 0; i_bhs < nr_bhs; i_bhs++) { + struct buffer_head *tbh = bhs[i_bhs]; + + wait_on_buffer(tbh); + if (unlikely(!buffer_uptodate(tbh))) { + err = -EIO; + /* + * Set the buffer uptodate so the page and buffer + * states do not become out of sync. + */ + if (PageUptodate(page)) + set_buffer_uptodate(tbh); + } + } + /* If @sync, now synchronize the mft mirror. */ + if (sync && ni->mft_no < vol->mftmirr_size) + ntfs_sync_mft_mirror(vol, ni->mft_no, m, sync); + /* Remove the mst protection fixups again. */ + post_write_mst_fixup((NTFS_RECORD*)m); + flush_dcache_mft_record_page(ni); + if (unlikely(err)) { + /* I/O error during writing. This is really bad! */ + ntfs_error(vol->sb, "I/O error while writing mft record " + "0x%lx! Marking base inode as bad. You " + "should unmount the volume and run chkdsk.", + ni->mft_no); + goto err_out; + } +done: + ntfs_debug("Done."); + return 0; +cleanup_out: + /* Clean the buffers. */ + for (i_bhs = 0; i_bhs < nr_bhs; i_bhs++) + clear_buffer_dirty(bhs[i_bhs]); +err_out: + /* + * Current state: all buffers are clean, unlocked, and uptodate. + * The caller should mark the base inode as bad so that no more i/o + * happens. ->clear_inode() will still be invoked so all extent inodes + * and other allocated memory will be freed. + */ + if (err == -ENOMEM) { + ntfs_error(vol->sb, "Not enough memory to write mft record. " + "Redirtying so the write is retried later."); + mark_mft_record_dirty(ni); + err = 0; + } else + NVolSetErrors(vol); + return err; +} + +/** + * ntfs_may_write_mft_record - check if an mft record may be written out + * @vol: [IN] ntfs volume on which the mft record to check resides + * @mft_no: [IN] mft record number of the mft record to check + * @m: [IN] mapped mft record to check + * @locked_ni: [OUT] caller has to unlock this ntfs inode if one is returned + * + * Check if the mapped (base or extent) mft record @m with mft record number + * @mft_no belonging to the ntfs volume @vol may be written out. If necessary + * and possible the ntfs inode of the mft record is locked and the base vfs + * inode is pinned. The locked ntfs inode is then returned in @locked_ni. The + * caller is responsible for unlocking the ntfs inode and unpinning the base + * vfs inode. + * + * Return TRUE if the mft record may be written out and FALSE if not. + * + * The caller has locked the page and cleared the uptodate flag on it which + * means that we can safely write out any dirty mft records that do not have + * their inodes in icache as determined by ilookup5() as anyone + * opening/creating such an inode would block when attempting to map the mft + * record in read_cache_page() until we are finished with the write out. + * + * Here is a description of the tests we perform: + * + * If the inode is found in icache we know the mft record must be a base mft + * record. If it is dirty, we do not write it and return FALSE as the vfs + * inode write paths will result in the access times being updated which would + * cause the base mft record to be redirtied and written out again. (We know + * the access time update will modify the base mft record because Windows + * chkdsk complains if the standard information attribute is not in the base + * mft record.) + * + * If the inode is in icache and not dirty, we attempt to lock the mft record + * and if we find the lock was already taken, it is not safe to write the mft + * record and we return FALSE. + * + * If we manage to obtain the lock we have exclusive access to the mft record, + * which also allows us safe writeout of the mft record. We then set + * @locked_ni to the locked ntfs inode and return TRUE. + * + * Note we cannot just lock the mft record and sleep while waiting for the lock + * because this would deadlock due to lock reversal (normally the mft record is + * locked before the page is locked but we already have the page locked here + * when we try to lock the mft record). + * + * If the inode is not in icache we need to perform further checks. + * + * If the mft record is not a FILE record or it is a base mft record, we can + * safely write it and return TRUE. + * + * We now know the mft record is an extent mft record. We check if the inode + * corresponding to its base mft record is in icache and obtain a reference to + * it if it is. If it is not, we can safely write it and return TRUE. + * + * We now have the base inode for the extent mft record. We check if it has an + * ntfs inode for the extent mft record attached and if not it is safe to write + * the extent mft record and we return TRUE. + * + * The ntfs inode for the extent mft record is attached to the base inode so we + * attempt to lock the extent mft record and if we find the lock was already + * taken, it is not safe to write the extent mft record and we return FALSE. + * + * If we manage to obtain the lock we have exclusive access to the extent mft + * record, which also allows us safe writeout of the extent mft record. We + * set the ntfs inode of the extent mft record clean and then set @locked_ni to + * the now locked ntfs inode and return TRUE. + * + * Note, the reason for actually writing dirty mft records here and not just + * relying on the vfs inode dirty code paths is that we can have mft records + * modified without them ever having actual inodes in memory. Also we can have + * dirty mft records with clean ntfs inodes in memory. None of the described + * cases would result in the dirty mft records being written out if we only + * relied on the vfs inode dirty code paths. And these cases can really occur + * during allocation of new mft records and in particular when the + * initialized_size of the $MFT/$DATA attribute is extended and the new space + * is initialized using ntfs_mft_record_format(). The clean inode can then + * appear if the mft record is reused for a new inode before it got written + * out. + */ +BOOL ntfs_may_write_mft_record(ntfs_volume *vol, const unsigned long mft_no, + const MFT_RECORD *m, ntfs_inode **locked_ni) +{ + struct super_block *sb = vol->sb; + struct inode *mft_vi = vol->mft_ino; + struct inode *vi; + ntfs_inode *ni, *eni, **extent_nis; + int i; + ntfs_attr na; + + ntfs_debug("Entering for inode 0x%lx.", mft_no); + /* + * Normally we do not return a locked inode so set @locked_ni to NULL. + */ + BUG_ON(!locked_ni); + *locked_ni = NULL; + /* + * Check if the inode corresponding to this mft record is in the VFS + * inode cache and obtain a reference to it if it is. + */ + ntfs_debug("Looking for inode 0x%lx in icache.", mft_no); + na.mft_no = mft_no; + na.name = NULL; + na.name_len = 0; + na.type = AT_UNUSED; + /* + * For inode 0, i.e. $MFT itself, we cannot use ilookup5() from here or + * we deadlock because the inode is already locked by the kernel + * (fs/fs-writeback.c::__sync_single_inode()) and ilookup5() waits + * until the inode is unlocked before returning it and it never gets + * unlocked because ntfs_should_write_mft_record() never returns. )-: + * Fortunately, we have inode 0 pinned in icache for the duration of + * the mount so we can access it directly. + */ + if (!mft_no) { + /* Balance the below iput(). */ + vi = igrab(mft_vi); + BUG_ON(vi != mft_vi); + } else + vi = ilookup5(sb, mft_no, (test_t)ntfs_test_inode, &na); + if (vi) { + ntfs_debug("Base inode 0x%lx is in icache.", mft_no); + /* The inode is in icache. */ + ni = NTFS_I(vi); + /* Take a reference to the ntfs inode. */ + atomic_inc(&ni->count); + /* If the inode is dirty, do not write this record. */ + if (NInoDirty(ni)) { + ntfs_debug("Inode 0x%lx is dirty, do not write it.", + mft_no); + atomic_dec(&ni->count); + iput(vi); + return FALSE; + } + ntfs_debug("Inode 0x%lx is not dirty.", mft_no); + /* The inode is not dirty, try to take the mft record lock. */ + if (unlikely(down_trylock(&ni->mrec_lock))) { + ntfs_debug("Mft record 0x%lx is already locked, do " + "not write it.", mft_no); + atomic_dec(&ni->count); + iput(vi); + return FALSE; + } + ntfs_debug("Managed to lock mft record 0x%lx, write it.", + mft_no); + /* + * The write has to occur while we hold the mft record lock so + * return the locked ntfs inode. + */ + *locked_ni = ni; + return TRUE; + } + ntfs_debug("Inode 0x%lx is not in icache.", mft_no); + /* The inode is not in icache. */ + /* Write the record if it is not a mft record (type "FILE"). */ + if (!ntfs_is_mft_record(m->magic)) { + ntfs_debug("Mft record 0x%lx is not a FILE record, write it.", + mft_no); + return TRUE; + } + /* |