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authorAnton Altaparmakov <anton@tuxera.com>2014-10-16 12:50:52 +0100
committerAnton Altaparmakov <anton@tuxera.com>2014-10-16 12:50:52 +0100
commit3f7fc6f2a2ba0f72a09e9f9999c3812fdee8fe70 (patch)
tree532bc0daf483485adf13dacb5ae69aa824848b48 /fs/ntfs
parent2b522cc16000c33d16bc76ee37e99ff9002a27be (diff)
NTFS: Add bmap address space operation needed for FIBMAP ioctl.
Signed-off-by: Anton Altaparmakov <anton@tuxera.com>
Diffstat (limited to 'fs/ntfs')
-rw-r--r--fs/ntfs/aops.c124
1 files changed, 124 insertions, 0 deletions
diff --git a/fs/ntfs/aops.c b/fs/ntfs/aops.c
index 6f0f98176b1..7521e11db72 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,