X-Git-Url: https://git.whamcloud.com/?p=fs%2Flustre-release.git;a=blobdiff_plain;f=lustre%2Futils%2Fliblustreapi_layout.c;h=ffee3fca8a24120f913123c62877831b12e0f19f;hp=531e0835564280160bec34a906e902c046dbfc05;hb=ff5eb304fa371d879da38621fac3aec7d4548a5e;hpb=aa1646a8a1c2a91a1571147994229b6413ee7acc

diff --git a/lustre/utils/liblustreapi_layout.c b/lustre/utils/liblustreapi_layout.c
index 531e083..ffee3fc 100644
--- a/lustre/utils/liblustreapi_layout.c
+++ b/lustre/utils/liblustreapi_layout.c
@@ -34,6 +34,7 @@
 #include <unistd.h>
 #include <errno.h>
 #include <limits.h>
+#include <assert.h>
 #include <sys/xattr.h>
 #include <sys/param.h>
 
@@ -59,6 +60,7 @@ struct llapi_layout_comp {
 	struct lu_extent	llc_extent;	/* [start, end) of component */
 	uint32_t		llc_id;		/* unique ID of component */
 	uint32_t		llc_flags;	/* LCME_FL_* flags */
+	uint64_t		llc_timestamp;	/* snapshot timestamp */
 	struct list_head	llc_list;	/* linked to the llapi_layout
 						   components list */
 };
@@ -147,6 +149,7 @@ llapi_layout_swab_lov_user_md(struct lov_user_md *lum, int lum_size)
 			ent = &comp_v1->lcm_entries[i];
 			__swab32s(&ent->lcme_id);
 			__swab32s(&ent->lcme_flags);
+			__swab64s(&ent->lcme_timestamp);
 			__swab64s(&ent->lcme_extent.e_start);
 			__swab64s(&ent->lcme_extent.e_end);
 			__swab32s(&ent->lcme_offset);
@@ -354,28 +357,134 @@ struct llapi_layout *llapi_layout_alloc(void)
 }
 
 /**
+ * Check if the given \a lum_size is large enough to hold the required
+ * fields in \a lum.
+ *
+ * \param[in] lum	the struct lov_user_md to check
+ * \param[in] lum_size	the number of bytes in \a lum
+ *
+ * \retval true		the \a lum_size is too small
+ * \retval false	the \a lum_size is large enough
+ */
+static bool llapi_layout_lum_truncated(struct lov_user_md *lum, size_t lum_size)
+{
+	uint32_t magic;
+
+	if (lum_size < sizeof(lum->lmm_magic))
+		return true;
+
+	if (lum->lmm_magic == LOV_MAGIC_V1 ||
+	    lum->lmm_magic == __swab32(LOV_MAGIC_V1))
+		magic = LOV_MAGIC_V1;
+	else if (lum->lmm_magic == LOV_MAGIC_V3 ||
+		 lum->lmm_magic == __swab32(LOV_MAGIC_V3))
+		magic = LOV_MAGIC_V3;
+	else if (lum->lmm_magic == LOV_MAGIC_COMP_V1 ||
+		 lum->lmm_magic == __swab32(LOV_MAGIC_COMP_V1))
+		magic = LOV_MAGIC_COMP_V1;
+	else
+		return true;
+
+	if (magic == LOV_MAGIC_V1 || magic == LOV_MAGIC_V3)
+		return lum_size < lov_user_md_size(0, magic);
+	else
+		return lum_size < sizeof(struct lov_comp_md_v1);
+}
+
+/* Verify if the objects count in lum is consistent with the
+ * stripe count in lum. It applies to regular file only. */
+static bool llapi_layout_lum_valid(struct lov_user_md *lum, int lum_size)
+{
+	struct lov_comp_md_v1 *comp_v1 = NULL;
+	int i, ent_count, obj_count;
+
+	if (lum->lmm_magic == LOV_MAGIC_COMP_V1) {
+		comp_v1 = (struct lov_comp_md_v1 *)lum;
+		ent_count = comp_v1->lcm_entry_count;
+	} else if (lum->lmm_magic == LOV_MAGIC_V1 ||
+		   lum->lmm_magic == LOV_MAGIC_V3) {
+		ent_count = 1;
+	} else {
+		return false;
+	}
+
+	for (i = 0; i < ent_count; i++) {
+		if (comp_v1) {
+			lum = (struct lov_user_md *)((char *)comp_v1 +
+				comp_v1->lcm_entries[i].lcme_offset);
+			lum_size = comp_v1->lcm_entries[i].lcme_size;
+		}
+		obj_count = llapi_layout_objects_in_lum(lum, lum_size);
+
+		if (comp_v1) {
+			if (!(comp_v1->lcm_entries[i].lcme_flags &
+				 LCME_FL_INIT) && obj_count != 0)
+				return false;
+		} else if (obj_count != lum->lmm_stripe_count) {
+			return false;
+		}
+	}
+	return true;
+}
+
+/**
  * Convert the data from a lov_user_md to a newly allocated llapi_layout.
  * The caller is responsible for freeing the returned pointer.
  *
- * \param[in] lum	LOV user metadata structure to copy data from
- * \param[in] lum_size	size the the lum passed in
+ * \param[in] lov_xattr		LOV user metadata xattr to copy data from
+ * \param[in] lov_xattr_size	size the lov_xattr_size passed in
+ * \param[in] flags		bitwise-or'd flags to control the behavior
  *
  * \retval		valid llapi_layout pointer on success
  * \retval		NULL if memory allocation fails
  */
-static struct llapi_layout *
-llapi_layout_from_lum(const struct lov_user_md *lum, int lum_size)
+struct llapi_layout *llapi_layout_get_by_xattr(void *lov_xattr,
+					       ssize_t lov_xattr_size,
+					       uint32_t flags)
 {
+	struct lov_user_md *lum = lov_xattr;
 	struct lov_comp_md_v1 *comp_v1 = NULL;
 	struct lov_comp_md_entry_v1 *ent;
 	struct lov_user_md *v1;
-	struct llapi_layout *layout;
+	struct llapi_layout *layout = NULL;
 	struct llapi_layout_comp *comp;
 	int i, ent_count = 0, obj_count;
 
-	layout = __llapi_layout_alloc();
-	if (layout == NULL)
+	if (lov_xattr == NULL || lov_xattr_size <= 0) {
+		errno = EINVAL;
+		return NULL;
+	}
+
+	/* Return an error if we got back a partial layout. */
+	if (llapi_layout_lum_truncated(lov_xattr, lov_xattr_size)) {
+		errno = ERANGE;
 		return NULL;
+	}
+
+#if __BYTE_ORDER == __BIG_ENDIAN
+	if (flags & LLAPI_LXF_COPY) {
+		lum = malloc(lov_xattr_size);
+		if (lum == NULL) {
+			errno = ENOMEM;
+			return NULL;
+		}
+		memcpy(lum, lov_xattr, lov_xattr_size);
+	}
+#endif
+
+	llapi_layout_swab_lov_user_md(lum, lov_xattr_size);
+
+	if ((flags & LLAPI_LXF_CHECK) &&
+	    !llapi_layout_lum_valid(lum, lov_xattr_size)) {
+		errno = EBADSLT;
+		goto out;
+	}
+
+	layout = __llapi_layout_alloc();
+	if (layout == NULL) {
+		errno = ENOMEM;
+		goto out;
+	}
 
 	if (lum->lmm_magic == LOV_MAGIC_COMP_V1) {
 		comp_v1 = (struct lov_comp_md_v1 *)lum;
@@ -389,11 +498,19 @@ llapi_layout_from_lum(const struct lov_user_md *lum, int lum_size)
 		   lum->lmm_magic == LOV_MAGIC_V3) {
 		ent_count = 1;
 		layout->llot_is_composite = false;
+
+		if (lov_xattr_size <= 0) {
+			errno = EINVAL;
+			goto out_layout;
+		}
+	} else {
+		errno = EOPNOTSUPP;
+		goto out_layout;
 	}
 
 	if (ent_count == 0) {
 		errno = EINVAL;
-		goto error;
+		goto out_layout;
 	}
 
 	v1 = (struct lov_user_md *)lum;
@@ -402,21 +519,23 @@ llapi_layout_from_lum(const struct lov_user_md *lum, int lum_size)
 			ent = &comp_v1->lcm_entries[i];
 			v1 = (struct lov_user_md *)((char *)comp_v1 +
 				ent->lcme_offset);
-			lum_size = ent->lcme_size;
+			lov_xattr_size = ent->lcme_size;
 		} else {
 			ent = NULL;
 		}
 
-		obj_count = llapi_layout_objects_in_lum(v1, lum_size);
+		obj_count = llapi_layout_objects_in_lum(v1, lov_xattr_size);
 		comp = __llapi_comp_alloc(obj_count);
 		if (comp == NULL)
-			goto error;
+			goto out_layout;
 
 		if (ent != NULL) {
 			comp->llc_extent.e_start = ent->lcme_extent.e_start;
 			comp->llc_extent.e_end = ent->lcme_extent.e_end;
 			comp->llc_id = ent->lcme_id;
 			comp->llc_flags = ent->lcme_flags;
+			if (comp->llc_flags & LCME_FL_NOSYNC)
+				comp->llc_timestamp = ent->lcme_timestamp;
 		} else {
 			comp->llc_extent.e_start = 0;
 			comp->llc_extent.e_end = LUSTRE_EOF;
@@ -426,6 +545,9 @@ llapi_layout_from_lum(const struct lov_user_md *lum, int lum_size)
 
 		if (v1->lmm_pattern == LOV_PATTERN_RAID0)
 			comp->llc_pattern = LLAPI_LAYOUT_RAID0;
+		else if (v1->lmm_pattern == (LOV_PATTERN_RAID0 |
+					 LOV_PATTERN_OVERSTRIPING))
+			comp->llc_pattern = LLAPI_LAYOUT_OVERSTRIPING;
 		else
 			/* Lustre only supports RAID0 for now. */
 			comp->llc_pattern = v1->lmm_pattern;
@@ -471,10 +593,38 @@ llapi_layout_from_lum(const struct lov_user_md *lum, int lum_size)
 		layout->llot_cur_comp = comp;
 	}
 
+out:
+	if (lum != lov_xattr)
+		free(lum);
 	return layout;
-error:
+out_layout:
 	llapi_layout_free(layout);
-	return NULL;
+	layout = NULL;
+	goto out;
+}
+
+__u32 llapi_pattern_to_lov(uint64_t pattern)
+{
+	__u32 lov_pattern;
+
+	switch (pattern) {
+	case LLAPI_LAYOUT_DEFAULT:
+		lov_pattern = LOV_PATTERN_RAID0;
+		break;
+	case LLAPI_LAYOUT_RAID0:
+		lov_pattern = LOV_PATTERN_RAID0;
+		break;
+	case LLAPI_LAYOUT_MDT:
+		lov_pattern = LOV_PATTERN_MDT;
+		break;
+	case LLAPI_LAYOUT_OVERSTRIPING:
+		lov_pattern = LOV_PATTERN_OVERSTRIPING | LOV_PATTERN_RAID0;
+		break;
+	default:
+		lov_pattern = EINVAL;
+	}
+
+	return lov_pattern;
 }
 
 /**
@@ -571,12 +721,11 @@ llapi_layout_to_lum(const struct llapi_layout *layout)
 		}
 
 		blob->lmm_magic = magic;
-		if (pattern == LLAPI_LAYOUT_DEFAULT)
-			blob->lmm_pattern = LOV_PATTERN_RAID0;
-		else if (pattern == LLAPI_LAYOUT_MDT)
-			blob->lmm_pattern = LOV_PATTERN_MDT;
-		else
-			blob->lmm_pattern = pattern;
+		blob->lmm_pattern = llapi_pattern_to_lov(pattern);
+		if (blob->lmm_pattern == EINVAL) {
+			errno = EINVAL;
+			goto error;
+		}
 
 		if (comp->llc_stripe_size == LLAPI_LAYOUT_DEFAULT)
 			blob->lmm_stripe_size = 0;
@@ -621,6 +770,8 @@ llapi_layout_to_lum(const struct llapi_layout *layout)
 			ent = &comp_v1->lcm_entries[ent_idx];
 			ent->lcme_id = comp->llc_id;
 			ent->lcme_flags = comp->llc_flags;
+			if (ent->lcme_flags & LCME_FL_NOSYNC)
+				ent->lcme_timestamp = comp->llc_timestamp;
 			ent->lcme_extent.e_start = comp->llc_extent.e_start;
 			ent->lcme_extent.e_end = comp->llc_extent.e_end;
 			ent->lcme_size = blob_size;
@@ -650,7 +801,7 @@ static void get_parent_dir(const char *path, char *buf, size_t size)
 {
 	char *p;
 
-	strncpy(buf, path, size);
+	strncpy(buf, path, size - 1);
 	p = strrchr(buf, '/');
 
 	if (p != NULL) {
@@ -748,77 +899,6 @@ static bool is_any_specified(const struct llapi_layout *layout)
 }
 
 /**
- * Check if the given \a lum_size is large enough to hold the required
- * fields in \a lum.
- *
- * \param[in] lum	the struct lov_user_md to check
- * \param[in] lum_size	the number of bytes in \a lum
- *
- * \retval true		the \a lum_size is too small
- * \retval false	the \a lum_size is large enough
- */
-static bool llapi_layout_lum_truncated(struct lov_user_md *lum, size_t lum_size)
-{
-	uint32_t magic;
-
-	if (lum_size < sizeof(lum->lmm_magic))
-		return true;
-
-	if (lum->lmm_magic == LOV_MAGIC_V1 ||
-	    lum->lmm_magic == __swab32(LOV_MAGIC_V1))
-		magic = LOV_MAGIC_V1;
-	else if (lum->lmm_magic == LOV_MAGIC_V3 ||
-		 lum->lmm_magic == __swab32(LOV_MAGIC_V3))
-		magic = LOV_MAGIC_V3;
-	else if (lum->lmm_magic == LOV_MAGIC_COMP_V1 ||
-		 lum->lmm_magic == __swab32(LOV_MAGIC_COMP_V1))
-		magic = LOV_MAGIC_COMP_V1;
-	else
-		return true;
-
-	if (magic == LOV_MAGIC_V1 || magic == LOV_MAGIC_V3)
-		return lum_size < lov_user_md_size(0, magic);
-	else
-		return lum_size < sizeof(struct lov_comp_md_v1);
-}
-
-/* Verify if the objects count in lum is consistent with the
- * stripe count in lum. It applies to regular file only. */
-static bool llapi_layout_lum_valid(struct lov_user_md *lum, int lum_size)
-{
-	struct lov_comp_md_v1 *comp_v1 = NULL;
-	int i, ent_count, obj_count;
-
-	if (lum->lmm_magic == LOV_MAGIC_COMP_V1) {
-		comp_v1 = (struct lov_comp_md_v1 *)lum;
-		ent_count = comp_v1->lcm_entry_count;
-	} else if (lum->lmm_magic == LOV_MAGIC_V1 ||
-		   lum->lmm_magic == LOV_MAGIC_V3) {
-		ent_count = 1;
-	} else {
-		return false;
-	}
-
-	for (i = 0; i < ent_count; i++) {
-		if (comp_v1) {
-			lum = (struct lov_user_md *)((char *)comp_v1 +
-				comp_v1->lcm_entries[i].lcme_offset);
-			lum_size = comp_v1->lcm_entries[i].lcme_size;
-		}
-		obj_count = llapi_layout_objects_in_lum(lum, lum_size);
-
-		if (comp_v1) {
-			if (!(comp_v1->lcm_entries[i].lcme_flags &
-				 LCME_FL_INIT) && obj_count != 0)
-				return false;
-		} else if (obj_count != lum->lmm_stripe_count) {
-			return false;
-		}
-	}
-	return true;
-}
-
-/**
  * Get the striping layout for the file referenced by file descriptor \a fd.
  *
  * If the filesystem does not support the "lustre." xattr namespace, the
@@ -857,14 +937,6 @@ struct llapi_layout *llapi_layout_get_by_fd(int fd, uint32_t flags)
 		goto out;
 	}
 
-	/* Return an error if we got back a partial layout. */
-	if (llapi_layout_lum_truncated(lum, bytes_read)) {
-		errno = EINTR;
-		goto out;
-	}
-
-	llapi_layout_swab_lov_user_md(lum, bytes_read);
-
 	/* Directories may have a positive non-zero lum->lmm_stripe_count
 	 * yet have an empty lum->lmm_objects array. For non-directories the
 	 * amount of data returned from the kernel must be consistent
@@ -872,12 +944,8 @@ struct llapi_layout *llapi_layout_get_by_fd(int fd, uint32_t flags)
 	if (fstat(fd, &st) < 0)
 		goto out;
 
-	if (!S_ISDIR(st.st_mode) && !llapi_layout_lum_valid(lum, bytes_read)) {
-		errno = EINTR;
-		goto out;
-	}
-
-	layout = llapi_layout_from_lum(lum, bytes_read);
+	layout = llapi_layout_get_by_xattr(lum, bytes_read,
+		S_ISDIR(st.st_mode) ? 0 : LLAPI_LXF_CHECK);
 out:
 	free(lum);
 	return layout;
@@ -1084,6 +1152,13 @@ static bool llapi_layout_stripe_count_is_valid(int64_t stripe_count)
 		 llapi_stripe_count_is_valid(stripe_count));
 }
 
+static bool llapi_layout_extension_size_is_valid(uint64_t ext_size)
+{
+	return (ext_size != 0 &&
+		llapi_stripe_size_is_aligned(ext_size) &&
+		!llapi_stripe_size_is_too_big(ext_size));
+}
+
 static bool llapi_layout_stripe_size_is_valid(uint64_t stripe_size)
 {
 	return stripe_size == LLAPI_LAYOUT_DEFAULT ||
@@ -1128,18 +1203,20 @@ int llapi_layout_stripe_count_set(struct llapi_layout *layout,
 }
 
 /**
- * Get the stripe size of \a layout.
+ * Get the stripe/extension size of \a layout.
  *
  * \param[in] layout	layout to get stripe size from
  * \param[out] size	integer to store stripe size in
+ * \param[in] extension flag if extenion size is requested
  *
  * \retval	0 on success
  * \retval	-1 if arguments are invalid
  */
-int llapi_layout_stripe_size_get(const struct llapi_layout *layout,
-				 uint64_t *size)
+static int layout_stripe_size_get(const struct llapi_layout *layout,
+				  uint64_t *size, bool extension)
 {
 	struct llapi_layout_comp *comp;
+	int comp_ext;
 
 	comp = __llapi_layout_cur_comp(layout);
 	if (comp == NULL)
@@ -1150,39 +1227,82 @@ int llapi_layout_stripe_size_get(const struct llapi_layout *layout,
 		return -1;
 	}
 
+	comp_ext = comp->llc_flags & LCME_FL_EXTENSION;
+	if ((comp_ext && !extension) || (!comp_ext && extension)) {
+		errno = EINVAL;
+		return -1;
+	}
+
 	*size = comp->llc_stripe_size;
+	if (comp->llc_flags & LCME_FL_EXTENSION)
+		*size *= SEL_UNIT_SIZE;
 
 	return 0;
 }
 
+int llapi_layout_stripe_size_get(const struct llapi_layout *layout,
+				 uint64_t *size)
+{
+	return layout_stripe_size_get(layout, size, false);
+}
+
+int llapi_layout_extension_size_get(const struct llapi_layout *layout,
+				    uint64_t *size)
+{
+	return layout_stripe_size_get(layout, size, true);
+}
+
 /**
- * Set the stripe size of \a layout.
+ * Set the stripe/extension size of \a layout.
  *
  * \param[in] layout	layout to set stripe size in
  * \param[in] size	value to be set
+ * \param[in] extension flag if extenion size is passed
  *
  * \retval	0 on success
  * \retval	-1 if arguments are invalid
  */
-int llapi_layout_stripe_size_set(struct llapi_layout *layout,
-				 uint64_t size)
+static int layout_stripe_size_set(struct llapi_layout *layout,
+				  uint64_t size, bool extension)
 {
 	struct llapi_layout_comp *comp;
+	int comp_ext;
 
 	comp = __llapi_layout_cur_comp(layout);
 	if (comp == NULL)
 		return -1;
 
-	if (!llapi_layout_stripe_size_is_valid(size)) {
+	comp_ext = comp->llc_flags & LCME_FL_EXTENSION;
+	if ((comp_ext && !extension) || (!comp_ext && extension)) {
 		errno = EINVAL;
 		return -1;
 	}
 
-	comp->llc_stripe_size = size;
+	if (comp_ext)
+		size /= SEL_UNIT_SIZE;
+
+	if ((comp_ext && !llapi_layout_extension_size_is_valid(size)) ||
+	    (!comp_ext && !llapi_layout_stripe_size_is_valid(size))) {
+		errno = EINVAL;
+		return -1;
+	}
 
+	comp->llc_stripe_size = size;
 	return 0;
 }
 
+int llapi_layout_stripe_size_set(struct llapi_layout *layout,
+				 uint64_t size)
+{
+	return layout_stripe_size_set(layout, size, false);
+}
+
+int llapi_layout_extension_size_set(struct llapi_layout *layout,
+				    uint64_t size)
+{
+	return layout_stripe_size_set(layout, size, true);
+}
+
 /**
  * Get the RAID pattern of \a layout.
  *
@@ -1230,7 +1350,8 @@ int llapi_layout_pattern_set(struct llapi_layout *layout, uint64_t pattern)
 		return -1;
 
 	if (pattern != LLAPI_LAYOUT_DEFAULT &&
-	    pattern != LLAPI_LAYOUT_RAID0 && pattern != LLAPI_LAYOUT_MDT) {
+	    pattern != LLAPI_LAYOUT_RAID0 && pattern != LLAPI_LAYOUT_MDT
+	    && pattern != LLAPI_LAYOUT_OVERSTRIPING) {
 		errno = EOPNOTSUPP;
 		return -1;
 	}
@@ -1430,7 +1551,7 @@ int llapi_layout_pool_name_set(struct llapi_layout *layout,
  *
  * \param[in] path		name of the file to open
  * \param[in] open_flags	open() flags
- * \param[in] mode		permissions to create new file with
+ * \param[in] mode		permissions to create file, filtered by umask
  * \param[in] layout		layout to create new file with
  *
  * \retval		non-negative file descriptor on successful open
@@ -1538,6 +1659,32 @@ int llapi_layout_flags_set(struct llapi_layout *layout, uint32_t flags)
 	return 0;
 }
 
+const char *llapi_layout_flags_string(uint32_t flags)
+{
+	switch (flags & LCM_FL_FLR_MASK) {
+	case LCM_FL_RDONLY:
+		return "ro";
+	case LCM_FL_WRITE_PENDING:
+		return "wp";
+	case LCM_FL_SYNC_PENDING:
+		return "sp";
+	}
+
+	return "0";
+}
+
+const __u16 llapi_layout_string_flags(char *string)
+{
+	if (strncmp(string, "ro", strlen(string)) == 0)
+		return LCM_FL_RDONLY;
+	if (strncmp(string, "wp", strlen(string)) == 0)
+		return LCM_FL_WRITE_PENDING;
+	if (strncmp(string, "sp", strlen(string)) == 0)
+		return LCM_FL_SYNC_PENDING;
+
+	return 0;
+}
+
 /**
  * llapi_layout_mirror_count_is_valid() - Check the validity of mirror count.
  * @count: Mirror count value to be checked.
@@ -1648,7 +1795,7 @@ int llapi_layout_comp_extent_set(struct llapi_layout *layout,
 	if (comp == NULL)
 		return -1;
 
-	if (start >= end) {
+	if (start > end) {
 		errno = EINVAL;
 		return -1;
 	}
@@ -1660,7 +1807,7 @@ int llapi_layout_comp_extent_set(struct llapi_layout *layout,
 	if (comp->llc_list.prev != &layout->llot_comp_list) {
 		prev = list_entry(comp->llc_list.prev, typeof(*prev),
 				  llc_list);
-		if (start != prev->llc_extent.e_end) {
+		if (start != 0 && start != prev->llc_extent.e_end) {
 			errno = EINVAL;
 			return -1;
 		}
@@ -1669,7 +1816,8 @@ int llapi_layout_comp_extent_set(struct llapi_layout *layout,
 	if (comp->llc_list.next != &layout->llot_comp_list) {
 		next = list_entry(comp->llc_list.next, typeof(*next),
 				  llc_list);
-		if (end != next->llc_extent.e_start) {
+		if (next->llc_extent.e_start != 0 &&
+		    end != next->llc_extent.e_start) {
 			errno = EINVAL;
 			return -1;
 		}
@@ -1848,6 +1996,37 @@ int llapi_layout_comp_add(struct llapi_layout *layout)
 
 	return 0;
 }
+/**
+ * Adds a first component of a mirror to \a layout.
+ * The \a layout will change it's current component pointer to
+ * the newly added component, and it'll be turned into a composite
+ * layout if it was not before the adding.
+ *
+ * \param[in] layout		existing composite or plain layout
+ *
+ * \retval	0 on success
+ * \retval	<0 if error occurs
+ */
+int llapi_layout_add_first_comp(struct llapi_layout *layout)
+{
+	struct llapi_layout_comp *comp, *new;
+
+	comp = __llapi_layout_cur_comp(layout);
+	if (comp == NULL)
+		return -1;
+
+	new = __llapi_comp_alloc(0);
+	if (new == NULL)
+		return -1;
+
+	new->llc_extent.e_start = 0;
+
+	list_add_tail(&new->llc_list, &layout->llot_comp_list);
+	layout->llot_cur_comp = new;
+	layout->llot_is_composite = true;
+
+	return 0;
+}
 
 /**
  * Deletes current component from the composite layout. The component
@@ -2231,7 +2410,13 @@ bool llapi_layout_is_composite(struct llapi_layout *layout)
 /**
  * Iterate every components in the @layout and call callback function @cb.
  *
- * \param[in]
+ * \param[in] layout	component layout list.
+ * \param[in] cb	callback for each component
+ * \param[in] cbdata	callback data
+ *
+ * \retval < 0				error happens during the iteration
+ * \retval LLAPI_LAYOUT_ITER_CONT	finished the iteration w/o error
+ * \retval LLAPI_LAYOUT_ITER_STOP	got something, stop the iteration
  */
 int llapi_layout_comp_iterate(struct llapi_layout *layout,
 			      llapi_layout_iter_cb cb, void *cbdata)
@@ -2242,7 +2427,13 @@ int llapi_layout_comp_iterate(struct llapi_layout *layout,
 	if (rc < 0)
 		return rc;
 
-	while (rc == 0) {
+	/**
+	 * make sure on success llapi_layout_comp_use() API returns 0 with
+	 * USE_FIRST.
+	 */
+	assert(rc == 0);
+
+	while (1) {
 		rc = cb(layout, cbdata);
 		if (rc != LLAPI_LAYOUT_ITER_CONT)
 			break;
@@ -2250,9 +2441,11 @@ int llapi_layout_comp_iterate(struct llapi_layout *layout,
 		rc = llapi_layout_comp_use(layout, LLAPI_LAYOUT_COMP_USE_NEXT);
 		if (rc < 0)
 			return rc;
+		else if (rc == 1)	/* reached the last comp */
+			return LLAPI_LAYOUT_ITER_CONT;
 	}
 
-	return rc >= 0 ? LLAPI_LAYOUT_ITER_CONT : rc;
+	return rc;
 }
 
 /**
@@ -2384,6 +2577,10 @@ int llapi_mirror_find_stale(struct llapi_layout *layout,
 			/* not in the specified mirror */
 			if (j == ids_nr)
 				goto next;
+		} else if (flags & LCME_FL_NOSYNC) {
+			/* if not specified mirrors, do not resync "nosync"
+			 * mirrors */
+			goto next;
 		}
 
 		rc = llapi_layout_comp_id_get(layout, &id);
@@ -2418,9 +2615,9 @@ error:
 }
 
 /* locate @layout to a valid component covering file [file_start, file_end) */
-static uint32_t llapi_mirror_find(struct llapi_layout *layout,
-				  uint64_t file_start, uint64_t file_end,
-				  uint64_t *endp)
+uint32_t llapi_mirror_find(struct llapi_layout *layout,
+			   uint64_t file_start, uint64_t file_end,
+			   uint64_t *endp)
 {
 	uint32_t mirror_id = 0;
 	int rc;
@@ -2473,12 +2670,21 @@ static uint32_t llapi_mirror_find(struct llapi_layout *layout,
 	return mirror_id;
 }
 
-ssize_t llapi_mirror_resync_one(int fd, struct llapi_layout *layout,
-				uint32_t dst, uint64_t start, uint64_t end)
+int llapi_mirror_resync_many(int fd, struct llapi_layout *layout,
+			     struct llapi_resync_comp *comp_array,
+			     int comp_size,  uint64_t start, uint64_t end)
 {
-	uint64_t mirror_end = 0;
-	ssize_t result = 0;
-	size_t count;
+	uint64_t count;
+	size_t page_size = sysconf(_SC_PAGESIZE);
+	const size_t buflen = 4 << 20; /* 4M */
+	void *buf;
+	uint64_t pos = start;
+	int i;
+	int rc;
+
+	rc = posix_memalign(&buf, page_size, buflen);
+	if (rc)
+		return -rc;
 
 	if (end == OBD_OBJECT_EOF)
 		count = OBD_OBJECT_EOF;
@@ -2487,30 +2693,99 @@ ssize_t llapi_mirror_resync_one(int fd, struct llapi_layout *layout,
 
 	while (count > 0) {
 		uint32_t src;
-		size_t to_copy;
-		ssize_t copied;
+		uint64_t mirror_end = 0;
+		uint64_t bytes_left;
+		ssize_t bytes_read;
+		size_t to_read;
+		size_t to_write;
 
-		src = llapi_mirror_find(layout, start, end, &mirror_end);
+		src = llapi_mirror_find(layout, pos, end, &mirror_end);
 		if (src == 0)
 			return -ENOENT;
 
-		if (mirror_end == OBD_OBJECT_EOF)
-			to_copy = count;
-		else
-			to_copy = MIN(count, mirror_end - start);
-
-		copied = llapi_mirror_copy(fd, src, dst, start, to_copy);
-		if (copied < 0)
-			return copied;
+		if (mirror_end == OBD_OBJECT_EOF) {
+			bytes_left = count;
+		} else {
+			bytes_left = MIN(count, mirror_end - pos);
+			bytes_left = ((bytes_left - 1) | (page_size - 1)) + 1;
+		}
+		to_read = MIN(buflen, bytes_left);
 
-		result += copied;
-		if (copied < to_copy) /* end of file */
+		bytes_read = llapi_mirror_read(fd, src, buf, to_read, pos);
+		if (bytes_read == 0) {
+			/* end of file */
+			break;
+		}
+		if (bytes_read < 0) {
+			rc = bytes_read;
 			break;
+		}
+
+		/* round up to page align to make direct IO happy. */
+		to_write = ((bytes_read - 1) | (page_size - 1)) + 1;
+
+		for (i = 0; i < comp_size; i++) {
+			ssize_t written;
+			off_t pos2 = pos;
+			size_t to_write2 = to_write;
+
+			/* skip non-overlapped component */
+			if (pos >= comp_array[i].lrc_end ||
+			    pos + to_write <= comp_array[i].lrc_start)
+				continue;
+
+			if (pos < comp_array[i].lrc_start)
+				pos2 = comp_array[i].lrc_start;
+
+			to_write2 -= pos2 - pos;
+
+			if ((pos + to_write) > comp_array[i].lrc_end)
+				to_write2 -= pos + to_write -
+					     comp_array[i].lrc_end;
+
+			written = llapi_mirror_write(fd,
+					comp_array[i].lrc_mirror_id,
+					buf + pos2 - pos,
+					to_write2, pos2);
+			if (written < 0) {
+				/**
+				 * this component is not written successfully,
+				 * mark it using its lrc_synced, it is supposed
+				 * to be false before getting here.
+				 *
+				 * And before this function returns, all
+				 * elements of comp_array will reverse their
+				 * lrc_synced flag to reflect their true
+				 * meanings.
+				 */
+				comp_array[i].lrc_synced = true;
+				continue;
+			}
+			assert(written == to_write2);
+		}
 
-		if (count != OBD_OBJECT_EOF)
-			count -= copied;
-		start += copied;
+		pos += bytes_read;
+		count -= bytes_read;
 	}
 
-	return result;
+	free(buf);
+
+	if (rc < 0) {
+		for (i = 0; i < comp_size; i++)
+			comp_array[i].lrc_synced = false;
+		return rc;
+	}
+
+	for (i = 0; i < comp_size; i++) {
+		comp_array[i].lrc_synced = !comp_array[i].lrc_synced;
+		if (comp_array[i].lrc_synced && pos & (page_size - 1)) {
+			rc = llapi_mirror_truncate(fd,
+					comp_array[i].lrc_mirror_id, pos);
+			if (rc < 0)
+				comp_array[i].lrc_synced = false;
+		}
+	}
+
+	/* partially successful is successful */
+	return 0;
 }