diff options
| -rw-r--r-- | fs/ntfs/aops.c | 124 |
1 files changed, 124 insertions, 0 deletions
diff --git a/fs/ntfs/aops.c b/fs/ntfs/aops.c index 6f0f98176b10..7521e11db728 100644 --- a/fs/ntfs/aops.c +++ b/fs/ntfs/aops.c @@ -1538,6 +1538,129 @@ err_out: #endif /* NTFS_RW */ /** + * ntfs_bmap - map logical file block to physical device block + * @mapping: address space mapping to which the block to be mapped belongs + * @block: logical block to map to its physical device block + * + * For regular, non-resident files (i.e. not compressed and not encrypted), map + * the logical @block belonging to the file described by the address space + * mapping @mapping to its physical device block. + * + * The size of the block is equal to the @s_blocksize field of the super block + * of the mounted file system which is guaranteed to be smaller than or equal + * to the cluster size thus the block is guaranteed to fit entirely inside the + * cluster which means we do not need to care how many contiguous bytes are + * available after the beginning of the block. + * + * Return the physical device block if the mapping succeeded or 0 if the block + * is sparse or there was an error. + * + * Note: This is a problem if someone tries to run bmap() on $Boot system file + * as that really is in block zero but there is nothing we can do. bmap() is + * just broken in that respect (just like it cannot distinguish sparse from + * not available or error). + */ +static sector_t ntfs_bmap(struct address_space *mapping, sector_t block) +{ + s64 ofs, size; + loff_t i_size; + LCN lcn; + unsigned long blocksize, flags; + ntfs_inode *ni = NTFS_I(mapping->host); + ntfs_volume *vol = ni->vol; + unsigned delta; + unsigned char blocksize_bits, cluster_size_shift; + + ntfs_debug("Entering for mft_no 0x%lx, logical block 0x%llx.", + ni->mft_no, (unsigned long long)block); + if (ni->type != AT_DATA || !NInoNonResident(ni) || NInoEncrypted(ni)) { + ntfs_error(vol->sb, "BMAP does not make sense for %s " + "attributes, returning 0.", + (ni->type != AT_DATA) ? "non-data" : + (!NInoNonResident(ni) ? "resident" : + "encrypted")); + return 0; + } + /* None of these can happen. */ + BUG_ON(NInoCompressed(ni)); + BUG_ON(NInoMstProtected(ni)); + blocksize = vol->sb->s_blocksize; + blocksize_bits = vol->sb->s_blocksize_bits; + ofs = (s64)block << blocksize_bits; + read_lock_irqsave(&ni->size_lock, flags); + size = ni->initialized_size; + i_size = i_size_read(VFS_I(ni)); + read_unlock_irqrestore(&ni->size_lock, flags); + /* + * If the offset is outside the initialized size or the block straddles + * the initialized size then pretend it is a hole unless the + * initialized size equals the file size. + */ + if (unlikely(ofs >= size || (ofs + blocksize > size && size < i_size))) + goto hole; + cluster_size_shift = vol->cluster_size_bits; + down_read(&ni->runlist.lock); + lcn = ntfs_attr_vcn_to_lcn_nolock(ni, ofs >> cluster_size_shift, false); + up_read(&ni->runlist.lock); + if (unlikely(lcn < LCN_HOLE)) { + /* + * Step down to an integer to avoid gcc doing a long long + * comparision in the switch when we know @lcn is between + * LCN_HOLE and LCN_EIO (i.e. -1 to -5). + * + * Otherwise older gcc (at least on some architectures) will + * try to use __cmpdi2() which is of course not available in + * the kernel. + */ + switch ((int)lcn) { + case LCN_ENOENT: + /* + * If the offset is out of bounds then pretend it is a + * hole. + */ + goto hole; + case LCN_ENOMEM: + ntfs_error(vol->sb, "Not enough memory to complete " + "mapping for inode 0x%lx. " + "Returning 0.", ni->mft_no); + break; + default: + ntfs_error(vol->sb, "Failed to complete mapping for " + "inode 0x%lx. Run chkdsk. " + "Returning 0.", ni->mft_no); + break; + } + return 0; + } + if (lcn < 0) { + /* It is a hole. */ +hole: + ntfs_debug("Done (returning hole)."); + return 0; + } + /* + * The block is really allocated and fullfils all our criteria. + * Convert the cluster to units of block size and return the result. + */ + delta = ofs & vol->cluster_size_mask; + if (unlikely(sizeof(block) < sizeof(lcn))) { + block = lcn = ((lcn << cluster_size_shift) + delta) >> + blocksize_bits; + /* If the block number was truncated return 0. */ + if (unlikely(block != lcn)) { + ntfs_error(vol->sb, "Physical block 0x%llx is too " + "large to be returned, returning 0.", + (long long)lcn); + return 0; + } + } else + block = ((lcn << cluster_size_shift) + delta) >> + blocksize_bits; + ntfs_debug("Done (returning block 0x%llx).", (unsigned long long)lcn); + return block; +} + +/** * ntfs_normal_aops - address space operations for normal inodes and attributes * * Note these are not used for compressed or mst protected inodes and @@ -1549,6 +1672,7 @@ const struct address_space_operations ntfs_normal_aops = { .writepage = ntfs_writepage, .set_page_dirty = __set_page_dirty_buffers, #endif /* NTFS_RW */ + .bmap = ntfs_bmap, .migratepage = buffer_migrate_page, .is_partially_uptodate = block_is_partially_uptodate, .error_remove_page = generic_error_remove_page, |