NTFS: Add bmap address space operation needed for FIBMAP ioctl.
Signed-off-by: Anton Altaparmakov <anton@tuxera.com>
This commit is contained in:
Anton Altaparmakov
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2b522cc160
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1 changed files with 124 additions and 0 deletions
124
fs/ntfs/aops.c
124
fs/ntfs/aops.c
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@ -1537,6 +1537,129 @@ static int ntfs_writepage(struct page *page, struct writeback_control *wbc)
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#endif /* NTFS_RW */
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/**
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* ntfs_bmap - map logical file block to physical device block
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* @mapping: address space mapping to which the block to be mapped belongs
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* @block: logical block to map to its physical device block
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*
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* For regular, non-resident files (i.e. not compressed and not encrypted), map
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* the logical @block belonging to the file described by the address space
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* mapping @mapping to its physical device block.
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*
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* The size of the block is equal to the @s_blocksize field of the super block
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* of the mounted file system which is guaranteed to be smaller than or equal
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* to the cluster size thus the block is guaranteed to fit entirely inside the
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* cluster which means we do not need to care how many contiguous bytes are
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* available after the beginning of the block.
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*
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* Return the physical device block if the mapping succeeded or 0 if the block
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* is sparse or there was an error.
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*
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* Note: This is a problem if someone tries to run bmap() on $Boot system file
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* as that really is in block zero but there is nothing we can do. bmap() is
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* just broken in that respect (just like it cannot distinguish sparse from
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* not available or error).
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*/
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static sector_t ntfs_bmap(struct address_space *mapping, sector_t block)
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{
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s64 ofs, size;
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loff_t i_size;
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LCN lcn;
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unsigned long blocksize, flags;
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ntfs_inode *ni = NTFS_I(mapping->host);
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ntfs_volume *vol = ni->vol;
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unsigned delta;
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unsigned char blocksize_bits, cluster_size_shift;
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ntfs_debug("Entering for mft_no 0x%lx, logical block 0x%llx.",
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ni->mft_no, (unsigned long long)block);
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if (ni->type != AT_DATA || !NInoNonResident(ni) || NInoEncrypted(ni)) {
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ntfs_error(vol->sb, "BMAP does not make sense for %s "
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"attributes, returning 0.",
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(ni->type != AT_DATA) ? "non-data" :
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(!NInoNonResident(ni) ? "resident" :
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"encrypted"));
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return 0;
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}
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/* None of these can happen. */
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BUG_ON(NInoCompressed(ni));
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BUG_ON(NInoMstProtected(ni));
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blocksize = vol->sb->s_blocksize;
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blocksize_bits = vol->sb->s_blocksize_bits;
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ofs = (s64)block << blocksize_bits;
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read_lock_irqsave(&ni->size_lock, flags);
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size = ni->initialized_size;
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i_size = i_size_read(VFS_I(ni));
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read_unlock_irqrestore(&ni->size_lock, flags);
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/*
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* If the offset is outside the initialized size or the block straddles
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* the initialized size then pretend it is a hole unless the
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* initialized size equals the file size.
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*/
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if (unlikely(ofs >= size || (ofs + blocksize > size && size < i_size)))
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goto hole;
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cluster_size_shift = vol->cluster_size_bits;
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down_read(&ni->runlist.lock);
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lcn = ntfs_attr_vcn_to_lcn_nolock(ni, ofs >> cluster_size_shift, false);
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up_read(&ni->runlist.lock);
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if (unlikely(lcn < LCN_HOLE)) {
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/*
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* Step down to an integer to avoid gcc doing a long long
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* comparision in the switch when we know @lcn is between
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* LCN_HOLE and LCN_EIO (i.e. -1 to -5).
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*
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* Otherwise older gcc (at least on some architectures) will
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* try to use __cmpdi2() which is of course not available in
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* the kernel.
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*/
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switch ((int)lcn) {
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case LCN_ENOENT:
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/*
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* If the offset is out of bounds then pretend it is a
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* hole.
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*/
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goto hole;
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case LCN_ENOMEM:
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ntfs_error(vol->sb, "Not enough memory to complete "
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"mapping for inode 0x%lx. "
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"Returning 0.", ni->mft_no);
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break;
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default:
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ntfs_error(vol->sb, "Failed to complete mapping for "
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"inode 0x%lx. Run chkdsk. "
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"Returning 0.", ni->mft_no);
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break;
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}
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return 0;
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}
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if (lcn < 0) {
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/* It is a hole. */
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hole:
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ntfs_debug("Done (returning hole).");
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return 0;
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}
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/*
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* The block is really allocated and fullfils all our criteria.
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* Convert the cluster to units of block size and return the result.
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*/
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delta = ofs & vol->cluster_size_mask;
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if (unlikely(sizeof(block) < sizeof(lcn))) {
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block = lcn = ((lcn << cluster_size_shift) + delta) >>
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blocksize_bits;
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/* If the block number was truncated return 0. */
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if (unlikely(block != lcn)) {
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ntfs_error(vol->sb, "Physical block 0x%llx is too "
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"large to be returned, returning 0.",
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(long long)lcn);
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return 0;
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}
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} else
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block = ((lcn << cluster_size_shift) + delta) >>
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blocksize_bits;
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ntfs_debug("Done (returning block 0x%llx).", (unsigned long long)lcn);
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return block;
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}
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/**
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* ntfs_normal_aops - address space operations for normal inodes and attributes
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*
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@ -1549,6 +1672,7 @@ const struct address_space_operations ntfs_normal_aops = {
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.writepage = ntfs_writepage,
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.set_page_dirty = __set_page_dirty_buffers,
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#endif /* NTFS_RW */
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.bmap = ntfs_bmap,
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.migratepage = buffer_migrate_page,
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.is_partially_uptodate = block_is_partially_uptodate,
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.error_remove_page = generic_error_remove_page,
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