X-Git-Url: https://git.whamcloud.com/?a=blobdiff_plain;f=lustre%2Futils%2Fliblustreapi_layout.c;h=b9673567548f2f6e33675b93fc35f6827e4b5e31;hb=73f3bc50f72fb95cb48a9ccc47cf51c15350400f;hp=5f474b8f96bbc6862b52389837efc33bec67f286;hpb=b879bbc27db53ecc899f6007bf4fe0d993615def;p=fs%2Flustre-release.git

diff --git a/lustre/utils/liblustreapi_layout.c b/lustre/utils/liblustreapi_layout.c
index 5f474b8..b967356 100644
--- a/lustre/utils/liblustreapi_layout.c
+++ b/lustre/utils/liblustreapi_layout.c
@@ -23,7 +23,7 @@
  * Lustre files while hiding details of the internal data structures
  * from the user.
  *
- * Copyright (c) 2016, Intel Corporation.
+ * Copyright (c) 2016, 2017, Intel Corporation.
  *
  * Author: Ned Bass <bass6@llnl.gov>
  */
@@ -34,7 +34,9 @@
 #include <unistd.h>
 #include <errno.h>
 #include <limits.h>
+#include <assert.h>
 #include <sys/xattr.h>
+#include <sys/param.h>
 
 #include <libcfs/util/list.h>
 #include <lustre/lustreapi.h>
@@ -58,6 +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 */
 };
@@ -70,6 +73,7 @@ struct llapi_layout {
 	uint32_t	llot_gen;
 	uint32_t	llot_flags;
 	bool		llot_is_composite;
+	uint16_t	llot_mirror_count;
 	/* Cursor pointing to one of the components in llot_comp_list */
 	struct llapi_layout_comp *llot_cur_comp;
 	struct list_head	  llot_comp_list;
@@ -145,6 +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);
@@ -317,6 +322,7 @@ static struct llapi_layout *__llapi_layout_alloc(void)
 	layout->llot_gen = 0;
 	layout->llot_flags = 0;
 	layout->llot_is_composite = false;
+	layout->llot_mirror_count = 1;
 	layout->llot_cur_comp = NULL;
 	INIT_LIST_HEAD(&layout->llot_comp_list);
 
@@ -351,44 +357,160 @@ 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;
 		ent_count = comp_v1->lcm_entry_count;
+		layout->llot_gen = comp_v1->lcm_layout_gen;
 		layout->llot_is_composite = true;
+		layout->llot_mirror_count = comp_v1->lcm_mirror_count + 1;
 		layout->llot_gen = comp_v1->lcm_layout_gen;
 		layout->llot_flags = comp_v1->lcm_flags;
 	} else if (lum->lmm_magic == LOV_MAGIC_V1 ||
 		   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;
@@ -397,21 +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;
@@ -466,10 +590,14 @@ 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;
 }
 
 /**
@@ -506,7 +634,7 @@ llapi_layout_to_lum(const struct llapi_layout *layout)
 			comp_cnt++;
 
 		lum_size = sizeof(*comp_v1) + comp_cnt * sizeof(*ent);
-		lum = malloc(lum_size);
+		lum = calloc(lum_size, 1);
 		if (lum == NULL) {
 			errno = ENOMEM;
 			return NULL;
@@ -517,7 +645,7 @@ llapi_layout_to_lum(const struct llapi_layout *layout)
 		comp_v1->lcm_layout_gen = 0;
 		comp_v1->lcm_flags = layout->llot_flags;
 		comp_v1->lcm_entry_count = comp_cnt;
-		comp_v1->lcm_mirror_count = 0;
+		comp_v1->lcm_mirror_count = layout->llot_mirror_count - 1;
 		offset += lum_size;
 	}
 
@@ -567,8 +695,6 @@ llapi_layout_to_lum(const struct llapi_layout *layout)
 
 		blob->lmm_magic = magic;
 		if (pattern == LLAPI_LAYOUT_DEFAULT)
-			blob->lmm_pattern = 0;
-		else if (pattern == LLAPI_LAYOUT_RAID0)
 			blob->lmm_pattern = LOV_PATTERN_RAID0;
 		else if (pattern == LLAPI_LAYOUT_MDT)
 			blob->lmm_pattern = LOV_PATTERN_MDT;
@@ -618,6 +744,8 @@ 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;
@@ -734,7 +862,7 @@ static bool is_any_specified(const struct llapi_layout *layout)
 	if (comp == NULL)
 		return false;
 
-	if (layout->llot_is_composite)
+	if (layout->llot_is_composite || layout->llot_mirror_count != 1)
 		return true;
 
 	return comp->llc_pattern != LLAPI_LAYOUT_DEFAULT ||
@@ -745,77 +873,6 @@ 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
@@ -854,14 +911,6 @@ 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
@@ -869,12 +918,8 @@ 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;
@@ -1013,7 +1058,7 @@ struct llapi_layout *llapi_layout_get_by_path(const char *path, uint32_t flags)
  * \retval	NULL if an error occurs
  */
 struct llapi_layout *llapi_layout_get_by_fid(const char *lustre_dir,
-					     const lustre_fid *fid,
+					     const struct lu_fid *fid,
 					     uint32_t flags)
 {
 	int fd;
@@ -1227,8 +1272,7 @@ 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) {
 		errno = EOPNOTSUPP;
 		return -1;
 	}
@@ -1428,7 +1472,7 @@ 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
@@ -1511,6 +1555,17 @@ int llapi_layout_file_create(const char *path, int open_flags, int mode,
 				      layout);
 }
 
+int llapi_layout_flags_get(struct llapi_layout *layout, uint32_t *flags)
+{
+	if (layout->llot_magic != LLAPI_LAYOUT_MAGIC) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	*flags = layout->llot_flags;
+	return 0;
+}
+
 /**
  * Set flags to the header of a component layout.
  */
@@ -1525,6 +1580,93 @@ 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.
+ *
+ * This function checks the validity of mirror count.
+ *
+ * Return: true on success or false on failure.
+ */
+static bool llapi_layout_mirror_count_is_valid(uint16_t count)
+{
+	return count >= 0 && count <= LUSTRE_MIRROR_COUNT_MAX;
+}
+
+/**
+ * llapi_layout_mirror_count_get() - Get mirror count from the header of
+ *				     a layout.
+ * @layout: Layout to get mirror count from.
+ * @count:  Returned mirror count value.
+ *
+ * This function gets mirror count from the header of a layout.
+ *
+ * Return: 0 on success or -1 on failure.
+ */
+int llapi_layout_mirror_count_get(struct llapi_layout *layout,
+				  uint16_t *count)
+{
+	if (layout->llot_magic != LLAPI_LAYOUT_MAGIC) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	*count = layout->llot_mirror_count;
+	return 0;
+}
+
+/**
+ * llapi_layout_mirror_count_set() - Set mirror count to the header of a layout.
+ * @layout: Layout to set mirror count in.
+ * @count:  Mirror count value to be set.
+ *
+ * This function sets mirror count to the header of a layout.
+ *
+ * Return: 0 on success or -1 on failure.
+ */
+int llapi_layout_mirror_count_set(struct llapi_layout *layout,
+				  uint16_t count)
+{
+	if (layout->llot_magic != LLAPI_LAYOUT_MAGIC) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	if (!llapi_layout_mirror_count_is_valid(count)) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	layout->llot_mirror_count = count;
+	return 0;
+}
+
 /**
  * Fetch the start and end offset of the current layout component.
  *
@@ -1586,7 +1728,7 @@ 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;
 		}
@@ -1595,7 +1737,8 @@ 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;
 		}
@@ -1708,6 +1851,33 @@ int llapi_layout_comp_id_get(const struct llapi_layout *layout, uint32_t *id)
 }
 
 /**
+ * Return the mirror id of the current layout component.
+ *
+ * \param[in] layout	the layout component
+ * \param[out] id	stored the returned mirror ID
+ *
+ * \retval	0 on success
+ * \retval	<0 if error occurs
+ */
+int llapi_layout_mirror_id_get(const struct llapi_layout *layout, uint32_t *id)
+{
+	struct llapi_layout_comp *comp;
+
+	comp = __llapi_layout_cur_comp(layout);
+	if (comp == NULL)
+		return -1;
+
+	if (id == NULL) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	*id = mirror_id_of(comp->llc_id);
+
+	return 0;
+}
+
+/**
  * Adds a component to \a layout, the new component will be added to
  * the tail of components list and it'll inherit attributes of existing
  * ones. The \a layout will change it's current component pointer to
@@ -1734,12 +1904,6 @@ int llapi_layout_comp_add(struct llapi_layout *layout)
 	last = list_entry(layout->llot_comp_list.prev, typeof(*last),
 			  llc_list);
 
-	/* Inherit some attributes from existing component */
-	new->llc_stripe_size = comp->llc_stripe_size;
-	new->llc_stripe_count = comp->llc_stripe_count;
-	if (comp->llc_pool_name[0] != '\0')
-		strncpy(new->llc_pool_name, comp->llc_pool_name,
-			sizeof(comp->llc_pool_name));
 	if (new->llc_extent.e_end <= last->llc_extent.e_end) {
 		__llapi_comp_free(new);
 		errno = EINVAL;
@@ -1753,6 +1917,37 @@ 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
@@ -2024,13 +2219,100 @@ out:
  * comp->lcme_id value, which must be an unique component ID. The new
  * attributes are passed in by @comp and @valid is used to specify which
  * attributes in the component are going to be changed.
+ *
+ * \param[in] path	path name of the file
+ * \param[in] ids	An array of component IDs
+ * \param[in] flags	flags: LCME_FL_* or;
+ *			negative flags: (LCME_FL_NEG|LCME_FL_*)
+ * \param[in] count	Number of elements in ids and flags array
  */
-int llapi_layout_file_comp_set(const char *path,
-			       const struct llapi_layout *comp,
-			       uint32_t valid)
+int llapi_layout_file_comp_set(const char *path, uint32_t *ids, uint32_t *flags,
+			       size_t count)
 {
-	errno = EOPNOTSUPP;
-	return -1;
+	int rc = -1, fd = -1, i;
+	size_t lum_size;
+	struct llapi_layout *layout;
+	struct llapi_layout_comp *comp;
+	struct lov_user_md *lum = NULL;
+
+	if (path == NULL) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	if (!count)
+		return 0;
+
+	for (i = 0; i < count; i++) {
+		if (!ids[i] || !flags[i]) {
+			errno = EINVAL;
+			return -1;
+		}
+
+		if (ids[i] > LCME_ID_MAX || (flags[i] & ~LCME_KNOWN_FLAGS)) {
+			errno = EINVAL;
+			return -1;
+		}
+
+		/* do not allow to set or clear INIT flag */
+		if (flags[i] & LCME_FL_INIT) {
+			errno = EINVAL;
+			return -1;
+		}
+	}
+
+	layout = __llapi_layout_alloc();
+	if (layout == NULL)
+		return -1;
+
+	layout->llot_is_composite = true;
+	for (i = 0; i < count; i++) {
+		comp = __llapi_comp_alloc(0);
+		if (comp == NULL)
+			goto out;
+
+		comp->llc_id = ids[i];
+		comp->llc_flags = flags[i];
+
+		list_add_tail(&comp->llc_list, &layout->llot_comp_list);
+		layout->llot_cur_comp = comp;
+	}
+
+	lum = llapi_layout_to_lum(layout);
+	if (lum == NULL)
+		goto out;
+
+	lum_size = ((struct lov_comp_md_v1 *)lum)->lcm_size;
+
+	fd = open(path, O_RDWR);
+	if (fd < 0)
+		goto out;
+
+	/* flush cached pages from clients */
+	rc = llapi_file_flush(fd);
+	if (rc) {
+		errno = -rc;
+		rc = -1;
+		goto out_close;
+	}
+
+	rc = fsetxattr(fd, XATTR_LUSTRE_LOV".set.flags", lum, lum_size, 0);
+	if (rc < 0)
+		goto out_close;
+
+	rc = 0;
+
+out_close:
+	if (fd >= 0) {
+		int tmp_errno = errno;
+		close(fd);
+		errno = tmp_errno;
+	}
+out:
+	if (lum)
+		free(lum);
+	llapi_layout_free(layout);
+	return rc;
 }
 
 /**
@@ -2045,3 +2327,386 @@ bool llapi_layout_is_composite(struct llapi_layout *layout)
 {
 	return layout->llot_is_composite;
 }
+
+/**
+ * Iterate every components in the @layout and call callback function @cb.
+ *
+ * \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)
+{
+	int rc;
+
+	rc = llapi_layout_comp_use(layout, LLAPI_LAYOUT_COMP_USE_FIRST);
+	if (rc < 0)
+		return rc;
+
+	/**
+	 * 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;
+
+		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;
+}
+
+/**
+ * llapi_layout_merge() - Merge a composite layout into another one.
+ * @dst_layout: Destination composite layout.
+ * @src_layout: Source composite layout.
+ *
+ * This function copies all of the components from @src_layout and
+ * appends them to @dst_layout.
+ *
+ * Return: 0 on success or -1 on failure.
+ */
+int llapi_layout_merge(struct llapi_layout **dst_layout,
+		       const struct llapi_layout *src_layout)
+{
+	struct llapi_layout *new_layout = *dst_layout;
+	struct llapi_layout_comp *new = NULL;
+	struct llapi_layout_comp *comp = NULL;
+	int i = 0;
+
+	if (src_layout == NULL ||
+	    list_empty((struct list_head *)&src_layout->llot_comp_list))
+		return 0;
+
+	if (new_layout == NULL) {
+		new_layout = __llapi_layout_alloc();
+		if (new_layout == NULL) {
+			errno = ENOMEM;
+			return -1;
+		}
+	}
+
+	list_for_each_entry(comp, &src_layout->llot_comp_list, llc_list) {
+		new = __llapi_comp_alloc(0);
+		if (new == NULL) {
+			errno = ENOMEM;
+			goto error;
+		}
+
+		new->llc_pattern = comp->llc_pattern;
+		new->llc_stripe_size = comp->llc_stripe_size;
+		new->llc_stripe_count = comp->llc_stripe_count;
+		new->llc_stripe_offset = comp->llc_stripe_offset;
+
+		if (comp->llc_pool_name[0] != '\0')
+			strncpy(new->llc_pool_name, comp->llc_pool_name,
+				sizeof(new->llc_pool_name));
+
+		for (i = 0; i < comp->llc_objects_count; i++) {
+			if (__llapi_comp_objects_realloc(new,
+			    stripe_number_roundup(i)) < 0) {
+				errno = EINVAL;
+				__llapi_comp_free(new);
+				goto error;
+			}
+			new->llc_objects[i].l_ost_idx = \
+				comp->llc_objects[i].l_ost_idx;
+		}
+
+		new->llc_objects_count = comp->llc_objects_count;
+		new->llc_extent.e_start = comp->llc_extent.e_start;
+		new->llc_extent.e_end = comp->llc_extent.e_end;
+		new->llc_id = comp->llc_id;
+		new->llc_flags = comp->llc_flags;
+
+		list_add_tail(&new->llc_list, &new_layout->llot_comp_list);
+		new_layout->llot_cur_comp = new;
+	}
+	new_layout->llot_is_composite = true;
+
+	*dst_layout = new_layout;
+	return 0;
+error:
+	llapi_layout_free(new_layout);
+	return -1;
+}
+
+/**
+ * Find all stale components.
+ *
+ * \param[in] layout		component layout list.
+ * \param[out] comp		array of stale component info.
+ * \param[in] comp_size		array size of @comp.
+ * \param[in] mirror_ids	array of mirror id that only components
+ *				belonging to these mirror will be collected.
+ * \param[in] ids_nr		number of mirror ids array.
+ *
+ * \retval		number of component info collected on sucess or
+ *			an error code on failure.
+ */
+int llapi_mirror_find_stale(struct llapi_layout *layout,
+		struct llapi_resync_comp *comp, size_t comp_size,
+		__u16 *mirror_ids, int ids_nr)
+{
+	int idx = 0;
+	int rc;
+
+	rc = llapi_layout_comp_use(layout, LLAPI_LAYOUT_COMP_USE_FIRST);
+	if (rc < 0)
+		goto error;
+
+	while (rc == 0) {
+		uint32_t id;
+		uint32_t mirror_id;
+		uint32_t flags;
+		uint64_t start, end;
+
+		rc = llapi_layout_comp_flags_get(layout, &flags);
+		if (rc < 0)
+			goto error;
+
+		if (!(flags & LCME_FL_STALE))
+			goto next;
+
+		rc = llapi_layout_mirror_id_get(layout, &mirror_id);
+		if (rc < 0)
+			goto error;
+
+		/* the caller only wants stale components from specific
+		 * mirrors */
+		if (ids_nr > 0) {
+			int j;
+
+			for (j = 0; j < ids_nr; j++) {
+				if (mirror_ids[j] == mirror_id)
+					break;
+			}
+
+			/* 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);
+		if (rc < 0)
+			goto error;
+
+		rc = llapi_layout_comp_extent_get(layout, &start, &end);
+		if (rc < 0)
+			goto error;
+
+		/* pack this component into @comp array */
+		comp[idx].lrc_id = id;
+		comp[idx].lrc_mirror_id = mirror_id;
+		comp[idx].lrc_start = start;
+		comp[idx].lrc_end = end;
+		idx++;
+
+		if (idx >= comp_size) {
+			rc = -EINVAL;
+			goto error;
+		}
+
+	next:
+		rc = llapi_layout_comp_use(layout, LLAPI_LAYOUT_COMP_USE_NEXT);
+		if (rc < 0) {
+			rc = -EINVAL;
+			goto error;
+		}
+	}
+error:
+	return rc < 0 ? rc : idx;
+}
+
+/* locate @layout to a valid component covering file [file_start, file_end) */
+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;
+
+	rc = llapi_layout_comp_use(layout, LLAPI_LAYOUT_COMP_USE_FIRST);
+	if (rc < 0)
+		return rc;
+
+	*endp = 0;
+	while (rc == 0) {
+		uint64_t start, end;
+		uint32_t flags, id, rid;
+
+		rc = llapi_layout_comp_flags_get(layout, &flags);
+		if (rc < 0)
+			return rc;
+
+		if (flags & LCME_FL_STALE)
+			goto next;
+
+		rc = llapi_layout_mirror_id_get(layout, &rid);
+		if (rc < 0)
+			return rc;
+
+		rc = llapi_layout_comp_id_get(layout, &id);
+		if (rc < 0)
+			return rc;
+
+		rc = llapi_layout_comp_extent_get(layout, &start, &end);
+		if (rc < 0)
+			return rc;
+
+		if (file_start >= start && file_start < end) {
+			if (!mirror_id)
+				mirror_id = rid;
+			else if (mirror_id != rid || *endp != start)
+				break;
+
+			file_start = *endp = end;
+			if (end >= file_end)
+				break;
+		}
+
+	next:
+		rc = llapi_layout_comp_use(layout, LLAPI_LAYOUT_COMP_USE_NEXT);
+		if (rc < 0)
+			return rc;
+	}
+
+	return mirror_id;
+}
+
+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 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;
+	else
+		count = end - start;
+
+	while (count > 0) {
+		uint32_t src;
+		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, pos, end, &mirror_end);
+		if (src == 0)
+			return -ENOENT;
+
+		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);
+
+		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);
+		}
+
+		pos += bytes_read;
+		count -= bytes_read;
+	}
+
+	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;
+}