1 files changed, 331 insertions, 0 deletions
diff --git a/fs/ntfs/aops.c b/fs/ntfs/aops.c
new file mode 100644
index 000000000..517d9a156
--- /dev/null
+++ b/fs/ntfs/aops.c
@@ -0,0 +1,331 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * NTFS kernel address space operations and page cache handling.
+ *
+ * Copyright (c) 2001-2014 Anton Altaparmakov and Tuxera Inc.
+ * Copyright (c) 2002 Richard Russon
+ * Copyright (c) 2025 LG Electronics Co., Ltd.
+ */
+
+#include <linux/writeback.h>
+
+#include "attrib.h"
+#include "mft.h"
+#include "ntfs.h"
+#include "debug.h"
+#include "iomap.h"
+
+static void ntfs_iomap_read_end_io(struct bio *bio)
+{
+	int error = blk_status_to_errno(bio->bi_status);
+	struct folio_iter iter;
+
+	bio_for_each_folio_all(iter, bio) {
+		struct folio *folio = iter.folio;
+		struct ntfs_inode *ni = NTFS_I(folio->mapping->host);
+		s64 init_size;
+		loff_t pos = folio_pos(folio);
+
+		init_size = ni->initialized_size;
+		if (pos + iter.offset < init_size &&
+		    pos + iter.offset + iter.length > init_size)
+			folio_zero_segment(folio, offset_in_folio(folio, init_size),
+					   iter.offset + iter.length);
+
+		iomap_finish_folio_read(folio, iter.offset, iter.length, error);
+	}
+	bio_put(bio);
+}
+
+static void ntfs_iomap_bio_submit_read(const struct iomap_iter *iter,
+		struct iomap_read_folio_ctx *ctx)
+{
+	iomap_bio_submit_read_endio(iter, ctx, ntfs_iomap_read_end_io);
+}
+
+static const struct iomap_read_ops ntfs_iomap_bio_read_ops = {
+	.read_folio_range	= iomap_bio_read_folio_range,
+	.submit_read		= ntfs_iomap_bio_submit_read,
+};
+
+/*
+ * ntfs_read_folio - Read data for a folio from the device
+ * @file:	open file to which the folio @folio belongs or NULL
+ * @folio:	page cache folio to fill with data
+ *
+ * This function handles reading data into the page cache. It first checks
+ * for specific ntfs attribute type like encryption and compression.
+ *
+ * - If the attribute is encrypted, access is denied (-EACCES) because
+ *   decryption is not supported in this path.
+ * - If the attribute is non-resident and compressed, the read operation is
+ *   delegated to ntfs_read_compressed_block().
+ * - For normal resident or non-resident attribute, it utilizes the generic
+ *   iomap infrastructure via iomap_bio_read_folio() to perform the I/O.
+ *
+ * Return: 0 on success, or -errno on error.
+ */
+static int ntfs_read_folio(struct file *file, struct folio *folio)
+{
+	struct ntfs_inode *ni = NTFS_I(folio->mapping->host);
+	struct iomap_read_folio_ctx ctx = {
+		.cur_folio = folio,
+		.ops = &ntfs_iomap_bio_read_ops,
+	};
+
+	/*
+	 * Only $DATA attributes can be encrypted and only unnamed $DATA
+	 * attributes can be compressed.  Index root can have the flags set but
+	 * this means to create compressed/encrypted files, not that the
+	 * attribute is compressed/encrypted.  Note we need to check for
+	 * AT_INDEX_ALLOCATION since this is the type of both directory and
+	 * index inodes.
+	 */
+	if (ni->type != AT_INDEX_ALLOCATION) {
+		/*
+		 * EFS-encrypted files are not supported.
+		 * (decryption/encryption is not implemented yet)
+		 */
+		if (NInoEncrypted(ni)) {
+			folio_unlock(folio);
+			return -EOPNOTSUPP;
+		}
+		if (NInoWofCompressed(ni)) {
+#ifdef CONFIG_NTFS_FS_WOF_COMPRESSION
+			return ntfs_read_wof_compressed_block(folio);
+#else
+			folio_unlock(folio);
+			return -EOPNOTSUPP;
+#endif
+		}
+		/* Compressed data streams are handled in compress.c. */
+		if (NInoNonResident(ni) && NInoCompressed(ni))
+			return ntfs_read_compressed_block(folio);
+	}
+
+	iomap_read_folio(&ntfs_read_iomap_ops, &ctx, NULL);
+	return 0;
+}
+
+/*
+ * 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;
+	s64 lcn;
+	unsigned long blocksize, flags;
+	struct ntfs_inode *ni = NTFS_I(mapping->host);
+	struct ntfs_volume *vol = ni->vol;
+	unsigned int delta;
+	unsigned char blocksize_bits;
+
+	ntfs_debug("Entering for mft_no 0x%llx, logical block 0x%llx.",
+			ni->mft_no, (unsigned long long)block);
+	if (ni->type != AT_DATA || !NInoNonResident(ni) || NInoEncrypted(ni) ||
+	    NInoWofCompressed(ni) || NInoMstProtected(ni)) {
+		ntfs_error(vol->sb, "BMAP does not make sense for %s attributes, returning 0.",
+				(ni->type != AT_DATA) ? "non-data" :
+				(!NInoNonResident(ni) ? "resident" :
+				(NInoWofCompressed(ni) ? "WOF-compressed" :
+				"encrypted")));
+		return 0;
+	}
+	/* None of these can happen. */
+	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;
+	down_read(&ni->runlist.lock);
+	lcn = ntfs_attr_vcn_to_lcn_nolock(ni, ntfs_bytes_to_cluster(vol, ofs),
+			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%llx. Returning 0.",
+				ni->mft_no);
+			break;
+		default:
+			ntfs_error(vol->sb,
+				"Failed to complete mapping for inode 0x%llx.  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 = (ntfs_cluster_to_bytes(vol, lcn) + 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 = (ntfs_cluster_to_bytes(vol, lcn) + delta) >>
+				blocksize_bits;
+	ntfs_debug("Done (returning block 0x%llx).", (unsigned long long)lcn);
+	return block;
+}
+
+static void ntfs_readahead(struct readahead_control *rac)
+{
+	struct address_space *mapping = rac->mapping;
+	struct inode *inode = mapping->host;
+	struct ntfs_inode *ni = NTFS_I(inode);
+	struct iomap_read_folio_ctx ctx = {
+		.ops = &ntfs_iomap_bio_read_ops,
+		.rac = rac,
+	};
+
+	/*
+	 * Resident files are not cached in the page cache,
+	 * and readahead is not implemented for compressed files.
+	 */
+	if (!NInoNonResident(ni) || NInoCompressed(ni) ||
+	    NInoWofCompressed(ni))
+		return;
+	iomap_readahead(&ntfs_read_iomap_ops, &ctx, NULL);
+}
+
+static int ntfs_writepages(struct address_space *mapping,
+		struct writeback_control *wbc)
+{
+	struct inode *inode = mapping->host;
+	struct ntfs_inode *ni = NTFS_I(inode);
+	struct iomap_writepage_ctx wpc = {
+		.inode		= mapping->host,
+		.wbc		= wbc,
+		.ops		= &ntfs_writeback_ops,
+	};
+	bool need_iput = false;
+	int ret;
+
+	if (NVolShutdown(ni->vol))
+		return -EIO;
+
+	if (!NInoNonResident(ni))
+		return 0;
+
+	/*
+	 * EFS-encrypted files are not supported.
+	 * (decryption/encryption is not implemented yet)
+	 */
+	if (NInoEncrypted(ni)) {
+		ntfs_debug("Encrypted I/O not supported");
+		return -EOPNOTSUPP;
+	}
+
+	/*
+	 * Prevent eviction in writeback to avoid deadlock in
+	 * ntfs_drop_big_inode().
+	 */
+	if ((ni->type == AT_DATA || ni->type == AT_INDEX_ALLOCATION) &&
+	    igrab(inode))
+		need_iput = true;
+
+	ret = iomap_writepages(&wpc);
+
+	if (need_iput)
+		iput(inode);
+
+	return ret;
+}
+
+static int ntfs_swap_activate(struct swap_info_struct *sis,
+		struct file *swap_file, sector_t *span)
+{
+	if (NInoWofCompressed(NTFS_I(file_inode(swap_file))))
+		return -EOPNOTSUPP;
+
+	return iomap_swapfile_activate(sis, swap_file, span,
+			&ntfs_read_iomap_ops);
+}
+
+const struct address_space_operations ntfs_aops = {
+	.read_folio		= ntfs_read_folio,
+	.readahead		= ntfs_readahead,
+	.writepages		= ntfs_writepages,
+	.dirty_folio		= iomap_dirty_folio,
+	.bmap			= ntfs_bmap,
+	.migrate_folio		= filemap_migrate_folio,
+	.is_partially_uptodate	= iomap_is_partially_uptodate,
+	.error_remove_folio	= generic_error_remove_folio,
+	.release_folio		= iomap_release_folio,
+	.invalidate_folio	= iomap_invalidate_folio,
+	.swap_activate          = ntfs_swap_activate,
+};
+
+const struct address_space_operations ntfs_mft_aops = {
+	.read_folio		= ntfs_read_folio,
+	.readahead		= ntfs_readahead,
+	.writepages		= ntfs_mft_writepages,
+	.dirty_folio		= iomap_dirty_folio,
+	.bmap			= ntfs_bmap,
+	.migrate_folio		= filemap_migrate_folio,
+	.is_partially_uptodate	= iomap_is_partially_uptodate,
+	.error_remove_folio	= generic_error_remove_folio,
+	.release_folio		= iomap_release_folio,
+	.invalidate_folio	= iomap_invalidate_folio,
+};