fs/ntfs3: Add support for the compression attribute

Support added for empty files and directories only.

Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>

Author: aalexandrovich

fs/ntfs3/attrib.c

@@ -2605,3 +2605,74 @@ int attr_force_nonresident(struct ntfs_inode *ni)
 
 	return err;
 }
+
+/*
+ * Change the compression of data attribute
+ */
+int attr_set_compress(struct ntfs_inode *ni, bool compr)
+{
+	struct ATTRIB *attr;
+	struct mft_inode *mi;
+
+	attr = ni_find_attr(ni, NULL, NULL, ATTR_DATA, NULL, 0, NULL, &mi);
+	if (!attr)
+		return -ENOENT;
+
+	if (is_attr_compressed(attr) == !!compr) {
+		/* Already required compressed state. */
+		return 0;
+	}
+
+	if (attr->non_res) {
+		u16 run_off;
+		u32 run_size;
+		char *run;
+
+		if (attr->nres.data_size) {
+			/*
+			 * There are rare cases when it possible to change
+			 * compress state without big changes.
+			 * TODO: Process these cases.
+			 */
+			return -EOPNOTSUPP;
+		}
+
+		run_off = le16_to_cpu(attr->nres.run_off);
+		run_size = le32_to_cpu(attr->size) - run_off;
+		run = Add2Ptr(attr, run_off);
+
+		if (!compr) {
+			/* remove field 'attr->nres.total_size'. */
+			memmove(run - 8, run, run_size);
+			run_off -= 8;
+		}
+
+		if (!mi_resize_attr(mi, attr, compr ? +8 : -8)) {
+			/*
+			 * Ignore rare case when there are no 8 bytes in record with attr.
+			 * TODO: split attribute.
+			 */
+			return -EOPNOTSUPP;
+		}
+
+		if (compr) {
+			/* Make a gap for 'attr->nres.total_size'. */
+			memmove(run + 8, run, run_size);
+			run_off += 8;
+			attr->nres.total_size = attr->nres.alloc_size;
+		}
+		attr->nres.run_off = cpu_to_le16(run_off);
+	}
+
+	/* Update data attribute flags. */
+	if (compr) {
+		attr->flags |= ATTR_FLAG_COMPRESSED;
+		attr->nres.c_unit = NTFS_LZNT_CUNIT;
+	} else {
+		attr->flags &= ~ATTR_FLAG_COMPRESSED;
+		attr->nres.c_unit = 0;
+	}
+	mi->dirty = true;
+
+	return 0;
+}

fs/ntfs3/file.c

@@ -82,13 +82,14 @@ int ntfs_fileattr_set(struct mnt_idmap *idmap, struct dentry *dentry,
 		      struct fileattr *fa)
 {
 	struct inode *inode = d_inode(dentry);
+	struct ntfs_inode *ni = ntfs_i(inode);
 	u32 flags = fa->flags;
 	unsigned int new_fl = 0;
 
 	if (fileattr_has_fsx(fa))
 		return -EOPNOTSUPP;
 
-	if (flags & ~(FS_IMMUTABLE_FL | FS_APPEND_FL))
+	if (flags & ~(FS_IMMUTABLE_FL | FS_APPEND_FL | FS_COMPR_FL))
 		return -EOPNOTSUPP;
 
 	if (flags & FS_IMMUTABLE_FL)
@@ -97,6 +98,15 @@ int ntfs_fileattr_set(struct mnt_idmap *idmap, struct dentry *dentry,
 	if (flags & FS_APPEND_FL)
 		new_fl |= S_APPEND;
 
+	/* Allowed to change compression for empty files and for directories only. */
+	if (!is_dedup(ni) && !is_encrypted(ni) &&
+	    (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))) {
+		/* Change compress state. */
+		int err = ni_set_compress(inode, flags & FS_COMPR_FL);
+		if (err)
+			return err;
+	}
+
 	inode_set_flags(inode, new_fl, S_IMMUTABLE | S_APPEND);
 
 	inode_set_ctime_current(inode);

fs/ntfs3/frecord.c

@@ -3450,3 +3450,75 @@ int ni_write_inode(struct inode *inode, int sync, const char *hint)
 
 	return 0;
 }
+
+/*
+ * ni_set_compress
+ *
+ * Helper for 'ntfs_fileattr_set'.
+ * Changes compression for empty files and directories only.
+ */
+int ni_set_compress(struct inode *inode, bool compr)
+{
+	int err;
+	struct ntfs_inode *ni = ntfs_i(inode);
+	struct ATTR_STD_INFO *std;
+	const char *bad_inode;
+
+	if (is_compressed(ni) == !!compr)
+		return 0;
+
+	if (is_sparsed(ni)) {
+		/* sparse and compress not compatible. */
+		return -EOPNOTSUPP;
+	}
+
+	if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode)) {
+		/*Skip other inodes. (symlink,fifo,...) */
+		return -EOPNOTSUPP;
+	}
+
+	bad_inode = NULL;
+
+	ni_lock(ni);
+
+	std = ni_std(ni);
+	if (!std) {
+		bad_inode = "no std";
+		goto out;
+	}
+
+	if (S_ISREG(inode->i_mode)) {
+		err = attr_set_compress(ni, compr);
+		if (err) {
+			if (err == -ENOENT) {
+				/* Fix on the fly? */
+				/* Each file must contain data attribute. */
+				bad_inode = "no data attribute";
+			}
+			goto out;
+		}
+	}
+
+	ni->std_fa = std->fa;
+	if (compr)
+		std->fa |= FILE_ATTRIBUTE_COMPRESSED;
+	else
+		std->fa &= ~FILE_ATTRIBUTE_COMPRESSED;
+
+	if (ni->std_fa != std->fa) {
+		ni->std_fa = std->fa;
+		ni->mi.dirty = true;
+	}
+	/* update duplicate information and directory entries in ni_write_inode.*/
+	ni->ni_flags |= NI_FLAG_UPDATE_PARENT;
+	err = 0;
+
+out:
+	ni_unlock(ni);
+	if (bad_inode) {
+		ntfs_bad_inode(inode, bad_inode);
+		err = -EINVAL;
+	}
+
+	return err;
+}

fs/ntfs3/ntfs_fs.h

@@ -453,6 +453,7 @@ int attr_collapse_range(struct ntfs_inode *ni, u64 vbo, u64 bytes);
 int attr_insert_range(struct ntfs_inode *ni, u64 vbo, u64 bytes);
 int attr_punch_hole(struct ntfs_inode *ni, u64 vbo, u64 bytes, u32 *frame_size);
 int attr_force_nonresident(struct ntfs_inode *ni);
+int attr_set_compress(struct ntfs_inode *ni, bool compr);
 
 /* Functions from attrlist.c */
 void al_destroy(struct ntfs_inode *ni);
@@ -588,6 +589,7 @@ int ni_rename(struct ntfs_inode *dir_ni, struct ntfs_inode *new_dir_ni,
 	      bool *is_bad);
 
 bool ni_is_dirty(struct inode *inode);
+int ni_set_compress(struct inode *inode, bool compr);
 
 /* Globals from fslog.c */
 bool check_index_header(const struct INDEX_HDR *hdr, size_t bytes);