Commit 3f7fc6f2 authored by Anton Altaparmakov's avatar Anton Altaparmakov

NTFS: Add bmap address space operation needed for FIBMAP ioctl.

Signed-off-by: default avatarAnton Altaparmakov <anton@tuxera.com>
parent 2b522cc1
......@@ -1537,6 +1537,129 @@ static int ntfs_writepage(struct page *page, struct writeback_control *wbc)
#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
*
......@@ -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,
......
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