btrfs-progs: check: fix the return value bug of cmd_check()
[platform/upstream/btrfs-progs.git] / cmds-check.c
index 18eecca..14816bd 100644 (file)
@@ -41,6 +41,7 @@
 #include "rbtree-utils.h"
 #include "backref.h"
 #include "ulist.h"
+#include "hash.h"
 
 enum task_position {
        TASK_EXTENTS,
@@ -3829,6 +3830,20 @@ out:
 #define ROOT_DIR_ERROR         (1<<1)  /* bad ROOT_DIR */
 #define DIR_ITEM_MISSING       (1<<2)  /* DIR_ITEM not found */
 #define DIR_ITEM_MISMATCH      (1<<3)  /* DIR_ITEM found but not match */
+#define INODE_REF_MISSING      (1<<4)  /* INODE_REF/INODE_EXTREF not found */
+#define INODE_ITEM_MISSING     (1<<5)  /* INODE_ITEM not found */
+#define INODE_ITEM_MISMATCH    (1<<6)  /* INODE_ITEM found but not match */
+#define FILE_EXTENT_ERROR      (1<<7)  /* bad FILE_EXTENT */
+#define ODD_CSUM_ITEM          (1<<8)  /* CSUM_ITEM error */
+#define CSUM_ITEM_MISSING      (1<<9)  /* CSUM_ITEM not found */
+#define LINK_COUNT_ERROR       (1<<10) /* INODE_ITEM nlink count error */
+#define NBYTES_ERROR           (1<<11) /* INODE_ITEM nbytes count error */
+#define ISIZE_ERROR            (1<<12) /* INODE_ITEM size count error */
+#define ORPHAN_ITEM            (1<<13) /* INODE_ITEM no reference */
+#define NO_INODE_ITEM          (1<<14) /* no inode_item */
+#define LAST_ITEM              (1<<15) /* Complete this tree traversal */
+#define ROOT_REF_MISSING       (1<<16) /* ROOT_REF not found */
+#define ROOT_REF_MISMATCH      (1<<17) /* ROOT_REF found but not match */
 
 /*
  * Find DIR_ITEM/DIR_INDEX for the given key and check it with the specified
@@ -3965,6 +3980,941 @@ out:
        return ret;
 }
 
+/*
+ * Traverse the given INODE_REF and call find_dir_item() to find related
+ * DIR_ITEM/DIR_INDEX.
+ *
+ * @root:      the root of the fs/file tree
+ * @ref_key:   the key of the INODE_REF
+ * @refs:      the count of INODE_REF
+ * @mode:      the st_mode of INODE_ITEM
+ *
+ * Return 0 if no error occurred.
+ */
+static int check_inode_ref(struct btrfs_root *root, struct btrfs_key *ref_key,
+                          struct extent_buffer *node, int slot, u64 *refs,
+                          int mode)
+{
+       struct btrfs_key key;
+       struct btrfs_inode_ref *ref;
+       char namebuf[BTRFS_NAME_LEN] = {0};
+       u32 total;
+       u32 cur = 0;
+       u32 len;
+       u32 name_len;
+       u64 index;
+       int ret, err = 0;
+
+       ref = btrfs_item_ptr(node, slot, struct btrfs_inode_ref);
+       total = btrfs_item_size_nr(node, slot);
+
+next:
+       /* Update inode ref count */
+       (*refs)++;
+
+       index = btrfs_inode_ref_index(node, ref);
+       name_len = btrfs_inode_ref_name_len(node, ref);
+       if (name_len <= BTRFS_NAME_LEN) {
+               len = name_len;
+       } else {
+               len = BTRFS_NAME_LEN;
+               warning("root %llu INODE_REF[%llu %llu] name too long",
+                       root->objectid, ref_key->objectid, ref_key->offset);
+       }
+
+       read_extent_buffer(node, namebuf, (unsigned long)(ref + 1), len);
+
+       /* Check root dir ref name */
+       if (index == 0 && strncmp(namebuf, "..", name_len)) {
+               error("root %llu INODE_REF[%llu %llu] ROOT_DIR name shouldn't be %s",
+                     root->objectid, ref_key->objectid, ref_key->offset,
+                     namebuf);
+               err |= ROOT_DIR_ERROR;
+       }
+
+       /* Find related DIR_INDEX */
+       key.objectid = ref_key->offset;
+       key.type = BTRFS_DIR_INDEX_KEY;
+       key.offset = index;
+       ret = find_dir_item(root, ref_key, &key, index, namebuf, len, mode);
+       err |= ret;
+
+       /* Find related dir_item */
+       key.objectid = ref_key->offset;
+       key.type = BTRFS_DIR_ITEM_KEY;
+       key.offset = btrfs_name_hash(namebuf, len);
+       ret = find_dir_item(root, ref_key, &key, index, namebuf, len, mode);
+       err |= ret;
+
+       len = sizeof(*ref) + name_len;
+       ref = (struct btrfs_inode_ref *)((char *)ref + len);
+       cur += len;
+       if (cur < total)
+               goto next;
+
+       return err;
+}
+
+/*
+ * Traverse the given INODE_EXTREF and call find_dir_item() to find related
+ * DIR_ITEM/DIR_INDEX.
+ *
+ * @root:      the root of the fs/file tree
+ * @ref_key:   the key of the INODE_EXTREF
+ * @refs:      the count of INODE_EXTREF
+ * @mode:      the st_mode of INODE_ITEM
+ *
+ * Return 0 if no error occurred.
+ */
+static int check_inode_extref(struct btrfs_root *root,
+                             struct btrfs_key *ref_key,
+                             struct extent_buffer *node, int slot, u64 *refs,
+                             int mode)
+{
+       struct btrfs_key key;
+       struct btrfs_inode_extref *extref;
+       char namebuf[BTRFS_NAME_LEN] = {0};
+       u32 total;
+       u32 cur = 0;
+       u32 len;
+       u32 name_len;
+       u64 index;
+       u64 parent;
+       int ret;
+       int err = 0;
+
+       extref = btrfs_item_ptr(node, slot, struct btrfs_inode_extref);
+       total = btrfs_item_size_nr(node, slot);
+
+next:
+       /* update inode ref count */
+       (*refs)++;
+       name_len = btrfs_inode_extref_name_len(node, extref);
+       index = btrfs_inode_extref_index(node, extref);
+       parent = btrfs_inode_extref_parent(node, extref);
+       if (name_len <= BTRFS_NAME_LEN) {
+               len = name_len;
+       } else {
+               len = BTRFS_NAME_LEN;
+               warning("root %llu INODE_EXTREF[%llu %llu] name too long",
+                       root->objectid, ref_key->objectid, ref_key->offset);
+       }
+       read_extent_buffer(node, namebuf, (unsigned long)(extref + 1), len);
+
+       /* Check root dir ref name */
+       if (index == 0 && strncmp(namebuf, "..", name_len)) {
+               error("root %llu INODE_EXTREF[%llu %llu] ROOT_DIR name shouldn't be %s",
+                     root->objectid, ref_key->objectid, ref_key->offset,
+                     namebuf);
+               err |= ROOT_DIR_ERROR;
+       }
+
+       /* find related dir_index */
+       key.objectid = parent;
+       key.type = BTRFS_DIR_INDEX_KEY;
+       key.offset = index;
+       ret = find_dir_item(root, ref_key, &key, index, namebuf, len, mode);
+       err |= ret;
+
+       /* find related dir_item */
+       key.objectid = parent;
+       key.type = BTRFS_DIR_ITEM_KEY;
+       key.offset = btrfs_name_hash(namebuf, len);
+       ret = find_dir_item(root, ref_key, &key, index, namebuf, len, mode);
+       err |= ret;
+
+       len = sizeof(*extref) + name_len;
+       extref = (struct btrfs_inode_extref *)((char *)extref + len);
+       cur += len;
+
+       if (cur < total)
+               goto next;
+
+       return err;
+}
+
+/*
+ * Find INODE_REF/INODE_EXTREF for the given key and check it with the specified
+ * DIR_ITEM/DIR_INDEX match.
+ *
+ * @root:      the root of the fs/file tree
+ * @key:       the key of the INODE_REF/INODE_EXTREF
+ * @name:      the name in the INODE_REF/INODE_EXTREF
+ * @namelen:   the length of name in the INODE_REF/INODE_EXTREF
+ * @index:     the index in the INODE_REF/INODE_EXTREF, for DIR_ITEM set index
+ * to (u64)-1
+ * @ext_ref:   the EXTENDED_IREF feature
+ *
+ * Return 0 if no error occurred.
+ * Return >0 for error bitmap
+ */
+static int find_inode_ref(struct btrfs_root *root, struct btrfs_key *key,
+                         char *name, int namelen, u64 index,
+                         unsigned int ext_ref)
+{
+       struct btrfs_path path;
+       struct btrfs_inode_ref *ref;
+       struct btrfs_inode_extref *extref;
+       struct extent_buffer *node;
+       char ref_namebuf[BTRFS_NAME_LEN] = {0};
+       u32 total;
+       u32 cur = 0;
+       u32 len;
+       u32 ref_namelen;
+       u64 ref_index;
+       u64 parent;
+       u64 dir_id;
+       int slot;
+       int ret;
+
+       btrfs_init_path(&path);
+       ret = btrfs_search_slot(NULL, root, key, &path, 0, 0);
+       if (ret) {
+               ret = INODE_REF_MISSING;
+               goto extref;
+       }
+
+       node = path.nodes[0];
+       slot = path.slots[0];
+
+       ref = btrfs_item_ptr(node, slot, struct btrfs_inode_ref);
+       total = btrfs_item_size_nr(node, slot);
+
+       /* Iterate all entry of INODE_REF */
+       while (cur < total) {
+               ret = INODE_REF_MISSING;
+
+               ref_namelen = btrfs_inode_ref_name_len(node, ref);
+               ref_index = btrfs_inode_ref_index(node, ref);
+               if (index != (u64)-1 && index != ref_index)
+                       goto next_ref;
+
+               if (ref_namelen <= BTRFS_NAME_LEN) {
+                       len = ref_namelen;
+               } else {
+                       len = BTRFS_NAME_LEN;
+                       warning("root %llu INODE %s[%llu %llu] name too long",
+                               root->objectid,
+                               key->type == BTRFS_INODE_REF_KEY ?
+                                       "REF" : "EXTREF",
+                               key->objectid, key->offset);
+               }
+               read_extent_buffer(node, ref_namebuf, (unsigned long)(ref + 1),
+                                  len);
+
+               if (len != namelen || strncmp(ref_namebuf, name, len))
+                       goto next_ref;
+
+               ret = 0;
+               goto out;
+next_ref:
+               len = sizeof(*ref) + ref_namelen;
+               ref = (struct btrfs_inode_ref *)((char *)ref + len);
+               cur += len;
+       }
+
+extref:
+       /* Skip if not support EXTENDED_IREF feature */
+       if (!ext_ref)
+               goto out;
+
+       btrfs_release_path(&path);
+       btrfs_init_path(&path);
+
+       dir_id = key->offset;
+       key->type = BTRFS_INODE_EXTREF_KEY;
+       key->offset = btrfs_extref_hash(dir_id, name, namelen);
+
+       ret = btrfs_search_slot(NULL, root, key, &path, 0, 0);
+       if (ret) {
+               ret = INODE_REF_MISSING;
+               goto out;
+       }
+
+       node = path.nodes[0];
+       slot = path.slots[0];
+
+       extref = btrfs_item_ptr(node, slot, struct btrfs_inode_extref);
+       cur = 0;
+       total = btrfs_item_size_nr(node, slot);
+
+       /* Iterate all entry of INODE_EXTREF */
+       while (cur < total) {
+               ret = INODE_REF_MISSING;
+
+               ref_namelen = btrfs_inode_extref_name_len(node, extref);
+               ref_index = btrfs_inode_extref_index(node, extref);
+               parent = btrfs_inode_extref_parent(node, extref);
+               if (index != (u64)-1 && index != ref_index)
+                       goto next_extref;
+
+               if (parent != dir_id)
+                       goto next_extref;
+
+               if (ref_namelen <= BTRFS_NAME_LEN) {
+                       len = ref_namelen;
+               } else {
+                       len = BTRFS_NAME_LEN;
+                       warning("Warning: root %llu INODE %s[%llu %llu] name too long\n",
+                               root->objectid,
+                               key->type == BTRFS_INODE_REF_KEY ?
+                                       "REF" : "EXTREF",
+                               key->objectid, key->offset);
+               }
+               read_extent_buffer(node, ref_namebuf,
+                                  (unsigned long)(extref + 1), len);
+
+               if (len != namelen || strncmp(ref_namebuf, name, len))
+                       goto next_extref;
+
+               ret = 0;
+               goto out;
+
+next_extref:
+               len = sizeof(*extref) + ref_namelen;
+               extref = (struct btrfs_inode_extref *)((char *)extref + len);
+               cur += len;
+
+       }
+out:
+       btrfs_release_path(&path);
+       return ret;
+}
+
+/*
+ * Traverse the given DIR_ITEM/DIR_INDEX and check related INODE_ITEM and
+ * call find_inode_ref() to check related INODE_REF/INODE_EXTREF.
+ *
+ * @root:      the root of the fs/file tree
+ * @key:       the key of the INODE_REF/INODE_EXTREF
+ * @size:      the st_size of the INODE_ITEM
+ * @ext_ref:   the EXTENDED_IREF feature
+ *
+ * Return 0 if no error occurred.
+ */
+static int check_dir_item(struct btrfs_root *root, struct btrfs_key *key,
+                         struct extent_buffer *node, int slot, u64 *size,
+                         unsigned int ext_ref)
+{
+       struct btrfs_dir_item *di;
+       struct btrfs_inode_item *ii;
+       struct btrfs_path path;
+       struct btrfs_key location;
+       char namebuf[BTRFS_NAME_LEN] = {0};
+       u32 total;
+       u32 cur = 0;
+       u32 len;
+       u32 name_len;
+       u32 data_len;
+       u8 filetype;
+       u32 mode;
+       u64 index;
+       int ret;
+       int err = 0;
+
+       /*
+        * For DIR_ITEM set index to (u64)-1, so that find_inode_ref
+        * ignore index check.
+        */
+       index = (key->type == BTRFS_DIR_INDEX_KEY) ? key->offset : (u64)-1;
+
+       di = btrfs_item_ptr(node, slot, struct btrfs_dir_item);
+       total = btrfs_item_size_nr(node, slot);
+
+       while (cur < total) {
+               data_len = btrfs_dir_data_len(node, di);
+               if (data_len)
+                       error("root %llu %s[%llu %llu] data_len shouldn't be %u",
+                             root->objectid, key->type == BTRFS_DIR_ITEM_KEY ?
+                             "DIR_ITEM" : "DIR_INDEX",
+                             key->objectid, key->offset, data_len);
+
+               name_len = btrfs_dir_name_len(node, di);
+               if (name_len <= BTRFS_NAME_LEN) {
+                       len = name_len;
+               } else {
+                       len = BTRFS_NAME_LEN;
+                       warning("root %llu %s[%llu %llu] name too long",
+                               root->objectid,
+                               key->type == BTRFS_DIR_ITEM_KEY ?
+                               "DIR_ITEM" : "DIR_INDEX",
+                               key->objectid, key->offset);
+               }
+               (*size) += name_len;
+
+               read_extent_buffer(node, namebuf, (unsigned long)(di + 1), len);
+               filetype = btrfs_dir_type(node, di);
+
+               btrfs_init_path(&path);
+               btrfs_dir_item_key_to_cpu(node, di, &location);
+
+               /* Ignore related ROOT_ITEM check */
+               if (location.type == BTRFS_ROOT_ITEM_KEY)
+                       goto next;
+
+               /* Check relative INODE_ITEM(existence/filetype) */
+               ret = btrfs_search_slot(NULL, root, &location, &path, 0, 0);
+               if (ret) {
+                       err |= INODE_ITEM_MISSING;
+                       error("root %llu %s[%llu %llu] couldn't find relative INODE_ITEM[%llu] namelen %u filename %s filetype %x",
+                             root->objectid, key->type == BTRFS_DIR_ITEM_KEY ?
+                             "DIR_ITEM" : "DIR_INDEX", key->objectid,
+                             key->offset, location.objectid, name_len,
+                             namebuf, filetype);
+                       goto next;
+               }
+
+               ii = btrfs_item_ptr(path.nodes[0], path.slots[0],
+                                   struct btrfs_inode_item);
+               mode = btrfs_inode_mode(path.nodes[0], ii);
+
+               if (imode_to_type(mode) != filetype) {
+                       err |= INODE_ITEM_MISMATCH;
+                       error("root %llu %s[%llu %llu] relative INODE_ITEM filetype mismatch namelen %u filename %s filetype %d",
+                             root->objectid, key->type == BTRFS_DIR_ITEM_KEY ?
+                             "DIR_ITEM" : "DIR_INDEX", key->objectid,
+                             key->offset, name_len, namebuf, filetype);
+               }
+
+               /* Check relative INODE_REF/INODE_EXTREF */
+               location.type = BTRFS_INODE_REF_KEY;
+               location.offset = key->objectid;
+               ret = find_inode_ref(root, &location, namebuf, len,
+                                      index, ext_ref);
+               err |= ret;
+               if (ret & INODE_REF_MISSING)
+                       error("root %llu %s[%llu %llu] relative INODE_REF missing namelen %u filename %s filetype %d",
+                             root->objectid, key->type == BTRFS_DIR_ITEM_KEY ?
+                             "DIR_ITEM" : "DIR_INDEX", key->objectid,
+                             key->offset, name_len, namebuf, filetype);
+
+next:
+               btrfs_release_path(&path);
+               len = sizeof(*di) + name_len + data_len;
+               di = (struct btrfs_dir_item *)((char *)di + len);
+               cur += len;
+
+               if (key->type == BTRFS_DIR_INDEX_KEY && cur < total) {
+                       error("root %llu DIR_INDEX[%llu %llu] should contain only one entry",
+                             root->objectid, key->objectid, key->offset);
+                       break;
+               }
+       }
+
+       return err;
+}
+
+/*
+ * Check file extent datasum/hole, update the size of the file extents,
+ * check and update the last offset of the file extent.
+ *
+ * @root:      the root of fs/file tree.
+ * @fkey:      the key of the file extent.
+ * @nodatasum: INODE_NODATASUM feature.
+ * @size:      the sum of all EXTENT_DATA items size for this inode.
+ * @end:       the offset of the last extent.
+ *
+ * Return 0 if no error occurred.
+ */
+static int check_file_extent(struct btrfs_root *root, struct btrfs_key *fkey,
+                            struct extent_buffer *node, int slot,
+                            unsigned int nodatasum, u64 *size, u64 *end)
+{
+       struct btrfs_file_extent_item *fi;
+       u64 disk_bytenr;
+       u64 disk_num_bytes;
+       u64 extent_num_bytes;
+       u64 found;
+       unsigned int extent_type;
+       unsigned int is_hole;
+       int ret;
+       int err = 0;
+
+       fi = btrfs_item_ptr(node, slot, struct btrfs_file_extent_item);
+
+       extent_type = btrfs_file_extent_type(node, fi);
+       /* Skip if file extent is inline */
+       if (extent_type == BTRFS_FILE_EXTENT_INLINE) {
+               struct btrfs_item *e = btrfs_item_nr(slot);
+               u32 item_inline_len;
+
+               item_inline_len = btrfs_file_extent_inline_item_len(node, e);
+               extent_num_bytes = btrfs_file_extent_inline_len(node, slot, fi);
+               if (extent_num_bytes == 0 ||
+                   extent_num_bytes != item_inline_len)
+                       err |= FILE_EXTENT_ERROR;
+               *size += extent_num_bytes;
+               return err;
+       }
+
+       /* Check extent type */
+       if (extent_type != BTRFS_FILE_EXTENT_REG &&
+                       extent_type != BTRFS_FILE_EXTENT_PREALLOC) {
+               err |= FILE_EXTENT_ERROR;
+               error("root %llu EXTENT_DATA[%llu %llu] type bad",
+                     root->objectid, fkey->objectid, fkey->offset);
+               return err;
+       }
+
+       /* Check REG_EXTENT/PREALLOC_EXTENT */
+       disk_bytenr = btrfs_file_extent_disk_bytenr(node, fi);
+       disk_num_bytes = btrfs_file_extent_disk_num_bytes(node, fi);
+       extent_num_bytes = btrfs_file_extent_num_bytes(node, fi);
+       is_hole = (disk_bytenr == 0) && (disk_num_bytes == 0);
+
+       /* Check EXTENT_DATA datasum */
+       ret = count_csum_range(root, disk_bytenr, disk_num_bytes, &found);
+       if (found > 0 && nodatasum) {
+               err |= ODD_CSUM_ITEM;
+               error("root %llu EXTENT_DATA[%llu %llu] nodatasum shouldn't have datasum",
+                     root->objectid, fkey->objectid, fkey->offset);
+       } else if (extent_type == BTRFS_FILE_EXTENT_REG && !nodatasum &&
+                  !is_hole &&
+                  (ret < 0 || found == 0 || found < disk_num_bytes)) {
+               err |= CSUM_ITEM_MISSING;
+               error("root %llu EXTENT_DATA[%llu %llu] datasum missing",
+                     root->objectid, fkey->objectid, fkey->offset);
+       } else if (extent_type == BTRFS_FILE_EXTENT_PREALLOC && found > 0) {
+               err |= ODD_CSUM_ITEM;
+               error("root %llu EXTENT_DATA[%llu %llu] prealloc shouldn't have datasum",
+                     root->objectid, fkey->objectid, fkey->offset);
+       }
+
+       /* Check EXTENT_DATA hole */
+       if (no_holes && is_hole) {
+               err |= FILE_EXTENT_ERROR;
+               error("root %llu EXTENT_DATA[%llu %llu] shouldn't be hole",
+                     root->objectid, fkey->objectid, fkey->offset);
+       } else if (!no_holes && *end != fkey->offset) {
+               err |= FILE_EXTENT_ERROR;
+               error("root %llu EXTENT_DATA[%llu %llu] interrupt",
+                     root->objectid, fkey->objectid, fkey->offset);
+       }
+
+       *end += extent_num_bytes;
+       if (!is_hole)
+               *size += extent_num_bytes;
+
+       return err;
+}
+
+/*
+ * Check INODE_ITEM and related ITEMs (the same inode number)
+ * 1. check link count
+ * 2. check inode ref/extref
+ * 3. check dir item/index
+ *
+ * @ext_ref:   the EXTENDED_IREF feature
+ *
+ * Return 0 if no error occurred.
+ * Return >0 for error or hit the traversal is done(by error bitmap)
+ */
+static int check_inode_item(struct btrfs_root *root, struct btrfs_path *path,
+                           unsigned int ext_ref)
+{
+       struct extent_buffer *node;
+       struct btrfs_inode_item *ii;
+       struct btrfs_key key;
+       u64 inode_id;
+       u32 mode;
+       u64 nlink;
+       u64 nbytes;
+       u64 isize;
+       u64 size = 0;
+       u64 refs = 0;
+       u64 extent_end = 0;
+       u64 extent_size = 0;
+       unsigned int dir;
+       unsigned int nodatasum;
+       int slot;
+       int ret;
+       int err = 0;
+
+       node = path->nodes[0];
+       slot = path->slots[0];
+
+       btrfs_item_key_to_cpu(node, &key, slot);
+       inode_id = key.objectid;
+
+       if (inode_id == BTRFS_ORPHAN_OBJECTID) {
+               ret = btrfs_next_item(root, path);
+               if (ret > 0)
+                       err |= LAST_ITEM;
+               return err;
+       }
+
+       ii = btrfs_item_ptr(node, slot, struct btrfs_inode_item);
+       isize = btrfs_inode_size(node, ii);
+       nbytes = btrfs_inode_nbytes(node, ii);
+       mode = btrfs_inode_mode(node, ii);
+       dir = imode_to_type(mode) == BTRFS_FT_DIR;
+       nlink = btrfs_inode_nlink(node, ii);
+       nodatasum = btrfs_inode_flags(node, ii) & BTRFS_INODE_NODATASUM;
+
+       while (1) {
+               ret = btrfs_next_item(root, path);
+               if (ret < 0) {
+                       /* out will fill 'err' rusing current statistics */
+                       goto out;
+               } else if (ret > 0) {
+                       err |= LAST_ITEM;
+                       goto out;
+               }
+
+               node = path->nodes[0];
+               slot = path->slots[0];
+               btrfs_item_key_to_cpu(node, &key, slot);
+               if (key.objectid != inode_id)
+                       goto out;
+
+               switch (key.type) {
+               case BTRFS_INODE_REF_KEY:
+                       ret = check_inode_ref(root, &key, node, slot, &refs,
+                                             mode);
+                       err |= ret;
+                       break;
+               case BTRFS_INODE_EXTREF_KEY:
+                       if (key.type == BTRFS_INODE_EXTREF_KEY && !ext_ref)
+                               warning("root %llu EXTREF[%llu %llu] isn't supported",
+                                       root->objectid, key.objectid,
+                                       key.offset);
+                       ret = check_inode_extref(root, &key, node, slot, &refs,
+                                                mode);
+                       err |= ret;
+                       break;
+               case BTRFS_DIR_ITEM_KEY:
+               case BTRFS_DIR_INDEX_KEY:
+                       if (!dir) {
+                               warning("root %llu INODE[%llu] mode %u shouldn't have DIR_INDEX[%llu %llu]",
+                                       root->objectid, inode_id,
+                                       imode_to_type(mode), key.objectid,
+                                       key.offset);
+                       }
+                       ret = check_dir_item(root, &key, node, slot, &size,
+                                            ext_ref);
+                       err |= ret;
+                       break;
+               case BTRFS_EXTENT_DATA_KEY:
+                       if (dir) {
+                               warning("root %llu DIR INODE[%llu] shouldn't EXTENT_DATA[%llu %llu]",
+                                       root->objectid, inode_id, key.objectid,
+                                       key.offset);
+                       }
+                       ret = check_file_extent(root, &key, node, slot,
+                                               nodatasum, &extent_size,
+                                               &extent_end);
+                       err |= ret;
+                       break;
+               case BTRFS_XATTR_ITEM_KEY:
+                       break;
+               default:
+                       error("ITEM[%llu %u %llu] UNKNOWN TYPE",
+                             key.objectid, key.type, key.offset);
+               }
+       }
+
+out:
+       /* verify INODE_ITEM nlink/isize/nbytes */
+       if (dir) {
+               if (nlink != 1) {
+                       err |= LINK_COUNT_ERROR;
+                       error("root %llu DIR INODE[%llu] shouldn't have more than one link(%llu)",
+                             root->objectid, inode_id, nlink);
+               }
+
+               /*
+                * Just a warning, as dir inode nbytes is just an
+                * instructive value.
+                */
+               if (!IS_ALIGNED(nbytes, root->nodesize)) {
+                       warning("root %llu DIR INODE[%llu] nbytes should be aligned to %u",
+                               root->objectid, inode_id, root->nodesize);
+               }
+
+               if (isize != size) {
+                       err |= ISIZE_ERROR;
+                       error("root %llu DIR INODE [%llu] size(%llu) not equal to %llu",
+                             root->objectid, inode_id, isize, size);
+               }
+       } else {
+               if (nlink != refs) {
+                       err |= LINK_COUNT_ERROR;
+                       error("root %llu INODE[%llu] nlink(%llu) not equal to inode_refs(%llu)",
+                             root->objectid, inode_id, nlink, refs);
+               } else if (!nlink) {
+                       err |= ORPHAN_ITEM;
+               }
+
+               if (!nbytes && !no_holes && extent_end < isize) {
+                       err |= NBYTES_ERROR;
+                       error("root %llu INODE[%llu] size (%llu) should have a file extent hole",
+                             root->objectid, inode_id, isize);
+               }
+
+               if (nbytes != extent_size) {
+                       err |= NBYTES_ERROR;
+                       error("root %llu INODE[%llu] nbytes(%llu) not equal to extent_size(%llu)",
+                             root->objectid, inode_id, nbytes, extent_size);
+               }
+       }
+
+       return err;
+}
+
+/*
+ * Iterate all item on the tree and call check_inode_item() to check.
+ *
+ * @root:      the root of the tree to be checked.
+ * @ext_ref:   the EXTENDED_IREF feature
+ *
+ * Return 0 if no error found.
+ * Return <0 for error.
+ * All internal error bitmap will be converted to -EIO, to avoid
+ * mixing negative and postive return value.
+ */
+static int check_fs_root_v2(struct btrfs_root *root, unsigned int ext_ref)
+{
+       struct btrfs_path *path;
+       struct btrfs_key key;
+       u64 inode_id;
+       int ret, err = 0;
+
+       path = btrfs_alloc_path();
+       if (!path)
+               return -ENOMEM;
+
+       key.objectid = 0;
+       key.type = 0;
+       key.offset = 0;
+
+       ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+       if (ret < 0)
+               goto out;
+
+       while (1) {
+               btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
+
+               /*
+                * All check must start with inode item, skip if not
+                */
+               if (key.type == BTRFS_INODE_ITEM_KEY) {
+                       ret = check_inode_item(root, path, ext_ref);
+                       err |= ret;
+                       if (err & LAST_ITEM)
+                               goto out;
+                       continue;
+               }
+               error("root %llu ITEM[%llu %u %llu] isn't INODE_ITEM, skip to next inode",
+                     root->objectid, key.objectid, key.type,
+                     key.offset);
+
+               err |= NO_INODE_ITEM;
+               inode_id = key.objectid;
+
+               /*
+                * skip to next inode
+                * TODO: Maybe search_slot() will be faster?
+                */
+               do {
+                       ret = btrfs_next_item(root, path);
+                       if (ret > 0) {
+                               goto out;
+                       } else if (ret < 0) {
+                               err = ret;
+                               goto out;
+                       }
+                       btrfs_item_key_to_cpu(path->nodes[0], &key,
+                                             path->slots[0]);
+               } while (inode_id == key.objectid);
+       }
+
+out:
+       err &= ~LAST_ITEM;
+       if (err && !ret)
+               ret = -EIO;
+       btrfs_free_path(path);
+       return ret;
+}
+
+/*
+ * Find the relative ref for root_ref and root_backref.
+ *
+ * @root:      the root of the root tree.
+ * @ref_key:   the key of the root ref.
+ *
+ * Return 0 if no error occurred.
+ */
+static int check_root_ref(struct btrfs_root *root, struct btrfs_key *ref_key,
+                         struct extent_buffer *node, int slot)
+{
+       struct btrfs_path *path;
+       struct btrfs_key key;
+       struct btrfs_root_ref *ref;
+       struct btrfs_root_ref *backref;
+       char ref_name[BTRFS_NAME_LEN] = {0};
+       char backref_name[BTRFS_NAME_LEN] = {0};
+       u64 ref_dirid;
+       u64 ref_seq;
+       u32 ref_namelen;
+       u64 backref_dirid;
+       u64 backref_seq;
+       u32 backref_namelen;
+       u32 len;
+       int ret;
+       int err = 0;
+
+       ref = btrfs_item_ptr(node, slot, struct btrfs_root_ref);
+       ref_dirid = btrfs_root_ref_dirid(node, ref);
+       ref_seq = btrfs_root_ref_sequence(node, ref);
+       ref_namelen = btrfs_root_ref_name_len(node, ref);
+
+       if (ref_namelen <= BTRFS_NAME_LEN) {
+               len = ref_namelen;
+       } else {
+               len = BTRFS_NAME_LEN;
+               warning("%s[%llu %llu] ref_name too long",
+                       ref_key->type == BTRFS_ROOT_REF_KEY ?
+                       "ROOT_REF" : "ROOT_BACKREF", ref_key->objectid,
+                       ref_key->offset);
+       }
+       read_extent_buffer(node, ref_name, (unsigned long)(ref + 1), len);
+
+       /* Find relative root_ref */
+       key.objectid = ref_key->offset;
+       key.type = BTRFS_ROOT_BACKREF_KEY + BTRFS_ROOT_REF_KEY - ref_key->type;
+       key.offset = ref_key->objectid;
+
+       path = btrfs_alloc_path();
+       ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
+       if (ret) {
+               err |= ROOT_REF_MISSING;
+               error("%s[%llu %llu] couldn't find relative ref",
+                     ref_key->type == BTRFS_ROOT_REF_KEY ?
+                     "ROOT_REF" : "ROOT_BACKREF",
+                     ref_key->objectid, ref_key->offset);
+               goto out;
+       }
+
+       backref = btrfs_item_ptr(path->nodes[0], path->slots[0],
+                                struct btrfs_root_ref);
+       backref_dirid = btrfs_root_ref_dirid(path->nodes[0], backref);
+       backref_seq = btrfs_root_ref_sequence(path->nodes[0], backref);
+       backref_namelen = btrfs_root_ref_name_len(path->nodes[0], backref);
+
+       if (backref_namelen <= BTRFS_NAME_LEN) {
+               len = backref_namelen;
+       } else {
+               len = BTRFS_NAME_LEN;
+               warning("%s[%llu %llu] ref_name too long",
+                       key.type == BTRFS_ROOT_REF_KEY ?
+                       "ROOT_REF" : "ROOT_BACKREF",
+                       key.objectid, key.offset);
+       }
+       read_extent_buffer(path->nodes[0], backref_name,
+                          (unsigned long)(backref + 1), len);
+
+       if (ref_dirid != backref_dirid || ref_seq != backref_seq ||
+           ref_namelen != backref_namelen ||
+           strncmp(ref_name, backref_name, len)) {
+               err |= ROOT_REF_MISMATCH;
+               error("%s[%llu %llu] mismatch relative ref",
+                     ref_key->type == BTRFS_ROOT_REF_KEY ?
+                     "ROOT_REF" : "ROOT_BACKREF",
+                     ref_key->objectid, ref_key->offset);
+       }
+out:
+       btrfs_free_path(path);
+       return err;
+}
+
+/*
+ * Check all fs/file tree in low_memory mode.
+ *
+ * 1. for fs tree root item, call check_fs_root_v2()
+ * 2. for fs tree root ref/backref, call check_root_ref()
+ *
+ * Return 0 if no error occurred.
+ */
+static int check_fs_roots_v2(struct btrfs_fs_info *fs_info)
+{
+       struct btrfs_root *tree_root = fs_info->tree_root;
+       struct btrfs_root *cur_root = NULL;
+       struct btrfs_path *path;
+       struct btrfs_key key;
+       struct extent_buffer *node;
+       unsigned int ext_ref;
+       int slot;
+       int ret;
+       int err = 0;
+
+       ext_ref = btrfs_fs_incompat(fs_info,
+                                   BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF);
+
+       path = btrfs_alloc_path();
+       if (!path)
+               return -ENOMEM;
+
+       key.objectid = BTRFS_FS_TREE_OBJECTID;
+       key.offset = 0;
+       key.type = BTRFS_ROOT_ITEM_KEY;
+
+       ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
+       if (ret < 0) {
+               err = ret;
+               goto out;
+       } else if (ret > 0) {
+               err = -ENOENT;
+               goto out;
+       }
+
+       while (1) {
+               node = path->nodes[0];
+               slot = path->slots[0];
+               btrfs_item_key_to_cpu(node, &key, slot);
+               if (key.objectid > BTRFS_LAST_FREE_OBJECTID)
+                       goto out;
+               if (key.type == BTRFS_ROOT_ITEM_KEY &&
+                   fs_root_objectid(key.objectid)) {
+                       if (key.objectid == BTRFS_TREE_RELOC_OBJECTID) {
+                               cur_root = btrfs_read_fs_root_no_cache(fs_info,
+                                                                      &key);
+                       } else {
+                               key.offset = (u64)-1;
+                               cur_root = btrfs_read_fs_root(fs_info, &key);
+                       }
+
+                       if (IS_ERR(cur_root)) {
+                               error("Fail to read fs/subvol tree: %lld",
+                                     key.objectid);
+                               err = -EIO;
+                               goto next;
+                       }
+
+                       ret = check_fs_root_v2(cur_root, ext_ref);
+                       err |= ret;
+
+                       if (key.objectid == BTRFS_TREE_RELOC_OBJECTID)
+                               btrfs_free_fs_root(cur_root);
+               } else if (key.type == BTRFS_ROOT_REF_KEY ||
+                               key.type == BTRFS_ROOT_BACKREF_KEY) {
+                       ret = check_root_ref(tree_root, &key, node, slot);
+                       err |= ret;
+               }
+next:
+               ret = btrfs_next_item(tree_root, path);
+               if (ret > 0)
+                       goto out;
+               if (ret < 0) {
+                       err = ret;
+                       goto out;
+               }
+       }
+
+out:
+       btrfs_free_path(path);
+       return err;
+}
+
 static int all_backpointers_checked(struct extent_record *rec, int print_errs)
 {
        struct list_head *cur = rec->backrefs.next;
@@ -11328,6 +12278,7 @@ int cmd_check(int argc, char **argv)
        u64 chunk_root_bytenr = 0;
        char uuidbuf[BTRFS_UUID_UNPARSED_SIZE];
        int ret;
+       int err = 0;
        u64 num;
        int init_csum_tree = 0;
        int readonly = 0;
@@ -11477,10 +12428,12 @@ int cmd_check(int argc, char **argv)
 
        if((ret = check_mounted(argv[optind])) < 0) {
                error("could not check mount status: %s", strerror(-ret));
+               err |= !!ret;
                goto err_out;
        } else if(ret) {
                error("%s is currently mounted, aborting", argv[optind]);
                ret = -EBUSY;
+               err |= !!ret;
                goto err_out;
        }
 
@@ -11493,6 +12446,7 @@ int cmd_check(int argc, char **argv)
        if (!info) {
                error("cannot open file system");
                ret = -EIO;
+               err |= !!ret;
                goto err_out;
        }
 
@@ -11541,9 +12495,11 @@ int cmd_check(int argc, char **argv)
                ret = ask_user("repair mode will force to clear out log tree, are you sure?");
                if (!ret) {
                        ret = 1;
+                       err |= !!ret;
                        goto close_out;
                }
                ret = zero_log_tree(root);
+               err |= !!ret;
                if (ret) {
                        error("failed to zero log tree: %d", ret);
                        goto close_out;
@@ -11555,6 +12511,7 @@ int cmd_check(int argc, char **argv)
                printf("Print quota groups for %s\nUUID: %s\n", argv[optind],
                       uuidbuf);
                ret = qgroup_verify_all(info);
+               err |= !!ret;
                if (ret == 0)
                        report_qgroups(1);
                goto close_out;
@@ -11563,6 +12520,7 @@ int cmd_check(int argc, char **argv)
                printf("Print extent state for subvolume %llu on %s\nUUID: %s\n",
                       subvolid, argv[optind], uuidbuf);
                ret = print_extent_state(info, subvolid);
+               err |= !!ret;
                goto close_out;
        }
        printf("Checking filesystem on %s\nUUID: %s\n", argv[optind], uuidbuf);
@@ -11571,6 +12529,7 @@ int cmd_check(int argc, char **argv)
            !extent_buffer_uptodate(info->dev_root->node) ||
            !extent_buffer_uptodate(info->chunk_root->node)) {
                error("critical roots corrupted, unable to check the filesystem");
+               err |= !!ret;
                ret = -EIO;
                goto close_out;
        }
@@ -11582,12 +12541,14 @@ int cmd_check(int argc, char **argv)
                if (IS_ERR(trans)) {
                        error("error starting transaction");
                        ret = PTR_ERR(trans);
+                       err |= !!ret;
                        goto close_out;
                }
 
                if (init_extent_tree) {
                        printf("Creating a new extent tree\n");
                        ret = reinit_extent_tree(trans, info);
+                       err |= !!ret;
                        if (ret)
                                goto close_out;
                }
@@ -11599,11 +12560,13 @@ int cmd_check(int argc, char **argv)
                                error("checksum tree initialization failed: %d",
                                                ret);
                                ret = -EIO;
+                               err |= !!ret;
                                goto close_out;
                        }
 
                        ret = fill_csum_tree(trans, info->csum_root,
                                             init_extent_tree);
+                       err |= !!ret;
                        if (ret) {
                                error("checksum tree refilling failed: %d", ret);
                                return -EIO;
@@ -11614,17 +12577,20 @@ int cmd_check(int argc, char **argv)
                 * extent entries for all of the items it finds.
                 */
                ret = btrfs_commit_transaction(trans, info->extent_root);
+               err |= !!ret;
                if (ret)
                        goto close_out;
        }
        if (!extent_buffer_uptodate(info->extent_root->node)) {
                error("critical: extent_root, unable to check the filesystem");
                ret = -EIO;
+               err |= !!ret;
                goto close_out;
        }
        if (!extent_buffer_uptodate(info->csum_root->node)) {
                error("critical: csum_root, unable to check the filesystem");
                ret = -EIO;
+               err |= !!ret;
                goto close_out;
        }
 
@@ -11634,11 +12600,13 @@ int cmd_check(int argc, char **argv)
                ret = check_chunks_and_extents_v2(root);
        else
                ret = check_chunks_and_extents(root);
+       err |= !!ret;
        if (ret)
                error(
                "errors found in extent allocation tree or chunk allocation");
 
        ret = repair_root_items(info);
+       err |= !!ret;
        if (ret < 0)
                goto close_out;
        if (repair) {
@@ -11651,6 +12619,7 @@ int cmd_check(int argc, char **argv)
                fprintf(stderr,
                        "Please run a filesystem check with the option --repair to fix them.\n");
                ret = 1;
+               err |= !!ret;
                goto close_out;
        }
 
@@ -11661,6 +12630,7 @@ int cmd_check(int argc, char **argv)
                        fprintf(stderr, "checking free space cache\n");
        }
        ret = check_space_cache(root);
+       err |= !!ret;
        if (ret)
                goto out;
 
@@ -11674,19 +12644,28 @@ int cmd_check(int argc, char **argv)
                                     BTRFS_FEATURE_INCOMPAT_NO_HOLES);
        if (!ctx.progress_enabled)
                fprintf(stderr, "checking fs roots\n");
-       ret = check_fs_roots(root, &root_cache);
+       if (check_mode == CHECK_MODE_LOWMEM)
+               ret = check_fs_roots_v2(root->fs_info);
+       else
+               ret = check_fs_roots(root, &root_cache);
+       err |= !!ret;
        if (ret)
                goto out;
 
        fprintf(stderr, "checking csums\n");
        ret = check_csums(root);
+       err |= !!ret;
        if (ret)
                goto out;
 
        fprintf(stderr, "checking root refs\n");
-       ret = check_root_refs(root, &root_cache);
-       if (ret)
-               goto out;
+       /* For low memory mode, check_fs_roots_v2 handles root refs */
+       if (check_mode != CHECK_MODE_LOWMEM) {
+               ret = check_root_refs(root, &root_cache);
+               err |= !!ret;
+               if (ret)
+                       goto out;
+       }
 
        while (repair && !list_empty(&root->fs_info->recow_ebs)) {
                struct extent_buffer *eb;
@@ -11695,6 +12674,7 @@ int cmd_check(int argc, char **argv)
                                      struct extent_buffer, recow);
                list_del_init(&eb->recow);
                ret = recow_extent_buffer(root, eb);
+               err |= !!ret;
                if (ret)
                        break;
        }
@@ -11704,32 +12684,33 @@ int cmd_check(int argc, char **argv)
 
                bad = list_first_entry(&delete_items, struct bad_item, list);
                list_del_init(&bad->list);
-               if (repair)
+               if (repair) {
                        ret = delete_bad_item(root, bad);
+                       err |= !!ret;
+               }
                free(bad);
        }
 
        if (info->quota_enabled) {
-               int err;
                fprintf(stderr, "checking quota groups\n");
-               err = qgroup_verify_all(info);
-               if (err)
+               ret = qgroup_verify_all(info);
+               err |= !!ret;
+               if (ret)
                        goto out;
                report_qgroups(0);
-               err = repair_qgroups(info, &qgroups_repaired);
+               ret = repair_qgroups(info, &qgroups_repaired);
+               err |= !!ret;
                if (err)
                        goto out;
+               ret = 0;
        }
 
        if (!list_empty(&root->fs_info->recow_ebs)) {
                error("transid errors in file system");
                ret = 1;
+               err |= !!ret;
        }
 out:
-       /* Don't override original ret */
-       if (!ret && qgroups_repaired)
-               ret = qgroups_repaired;
-
        if (found_old_backref) { /*
                 * there was a disk format change when mixed
                 * backref was in testing tree. The old format
@@ -11739,7 +12720,7 @@ out:
                       "The old format is not supported! *"
                       "\n * Please mount the FS in readonly mode, "
                       "backup data and re-format the FS. *\n\n");
-               ret = 1;
+               err |= 1;
        }
        printf("found %llu bytes used err is %d\n",
               (unsigned long long)bytes_used, ret);
@@ -11764,5 +12745,5 @@ err_out:
        if (ctx.progress_enabled)
                task_deinit(ctx.info);
 
-       return ret;
+       return err;
 }