make_ext4fs: write out super blocks at last for block devices

Change-Id: I93ee37a649aabff14464030efd88f79e1ae324f0
Signed-off-by: Eric Miao <emiao@nvidia.com>

diff --git a/ext4_utils/ext4_sb.h b/ext4_utils/ext4_sb.h
index 832fa33..159580d 100644 (file)
--- a/ext4_utils/ext4_sb.h
+++ b/ext4_utils/ext4_sb.h
@@ -25,6 +25,8 @@
 extern "C" {
 #endif
 
+#include <stdbool.h>
+
 struct fs_info {
        int64_t len;    /* If set to 0, ask the block device for the size,
                         * if less than 0, reserve that much space at the
@@ -41,6 +43,7 @@ struct fs_info {
        uint32_t bg_desc_reserve_blocks;
        const char *label;
        uint8_t no_journal;
+       bool block_device;      /* target fd is a block device? */
 };
 
 int ext4_parse_sb(struct ext4_super_block *sb, struct fs_info *info);

diff --git a/ext4_utils/ext4_utils.c b/ext4_utils/ext4_utils.c
index 3b22b81..0639293 100644 (file)
--- a/ext4_utils/ext4_utils.c
+++ b/ext4_utils/ext4_utils.c
@@ -168,10 +168,31 @@ void write_sb(int fd, unsigned long long offset, struct ext4_super_block *sb)
                critical_error("failed to write all of superblock");
 }
 
+static void block_device_write_sb(int fd)
+{
+       unsigned long long offset;
+       u32 i;
+
+       /* write out the backup superblocks */
+       for (i = 1; i < aux_info.groups; i++) {
+               if (ext4_bg_has_super_block(i)) {
+                       offset = info.block_size * (aux_info.first_data_block
+                               + i * info.blocks_per_group);
+                       write_sb(fd, offset, aux_info.backup_sb[i]);
+               }
+       }
+
+       /* write out the primary superblock */
+       write_sb(fd, 1024, aux_info.sb);
+}
+
 /* Write the filesystem image to a file */
 void write_ext4_image(int fd, int gz, int sparse, int crc)
 {
        sparse_file_write(ext4_sparse_file, fd, gz, sparse, crc);
+
+       if (info.block_device)
+               block_device_write_sb(fd);
 }
 
 /* Compute the rest of the parameters of the filesystem from the basic info */
@@ -203,7 +224,27 @@ void ext4_create_fs_aux_info()
                aux_info.len_blocks -= last_group_size;
        }
 
-       aux_info.sb = calloc(info.block_size, 1);
+       /* A zero-filled superblock to be written firstly to the block
+        * device to mark the file-system as invalid
+        */
+       aux_info.sb_zero = calloc(1, info.block_size);
+       if (!aux_info.sb_zero)
+               critical_error_errno("calloc");
+
+       /* The write_data* functions expect only block aligned calls.
+        * This is not an issue, except when we write out the super
+        * block on a system with a block size > 1K.  So, we need to
+        * deal with that here.
+        */
+       aux_info.sb_block = calloc(1, info.block_size);
+       if (!aux_info.sb_block)
+               critical_error_errno("calloc");
+
+       if (info.block_size > 1024)
+               aux_info.sb = (struct ext4_super_block *)((char *)aux_info.sb_block + 1024);
+       else
+               aux_info.sb = aux_info.sb_block;
+
        /* Alloc an array to hold the pointers to the backup superblocks */
        aux_info.backup_sb = calloc(aux_info.groups, sizeof(char *));
 
@@ -224,7 +265,8 @@ void ext4_free_fs_aux_info()
                if (aux_info.backup_sb[i])
                        free(aux_info.backup_sb[i]);
        }
-       free(aux_info.sb);
+       free(aux_info.sb_block);
+       free(aux_info.sb_zero);
        free(aux_info.bg_desc);
 }
 
@@ -324,8 +366,8 @@ void ext4_fill_in_sb(int real_uuid)
                                memcpy(aux_info.backup_sb[i], sb, info.block_size);
                                /* Update the block group nr of this backup superblock */
                                aux_info.backup_sb[i]->s_block_group_nr = i;
-                               sparse_file_add_data(ext4_sparse_file, aux_info.backup_sb[i],
-                                               info.block_size, group_start_block);
+                               ext4_queue_sb(group_start_block, info.block_device ?
+                                               aux_info.sb_zero : aux_info.backup_sb[i]);
                        }
                        sparse_file_add_data(ext4_sparse_file, aux_info.bg_desc,
                                aux_info.bg_desc_blocks * info.block_size,
@@ -341,22 +383,23 @@ void ext4_fill_in_sb(int real_uuid)
                aux_info.bg_desc[i].bg_free_inodes_count = sb->s_inodes_per_group;
                aux_info.bg_desc[i].bg_used_dirs_count = 0;
        }
+
+       /* Queue the primary superblock to be written out - if it's a block device,
+        * queue a zero-filled block first, the correct version of superblock will
+        * be written to the block device after all other blocks are written.
+        *
+        * The file-system on the block device will not be valid until the correct
+        * version of superblocks are written, this is to avoid the likelihood of a
+        * partially created file-system.
+        */
+       ext4_queue_sb(aux_info.first_data_block, info.block_device ?
+                               aux_info.sb_zero : aux_info.sb_block);
 }
 
-void ext4_queue_sb(void)
+
+void ext4_queue_sb(u64 start_block, struct ext4_super_block *sb)
 {
-       /* The write_data* functions expect only block aligned calls.
-        * This is not an issue, except when we write out the super
-        * block on a system with a block size > 1K.  So, we need to
-        * deal with that here.
-        */
-       if (info.block_size > 1024) {
-               u8 *buf = calloc(info.block_size, 1);
-               memcpy(buf + 1024, (u8*)aux_info.sb, 1024);
-               sparse_file_add_data(ext4_sparse_file, buf, info.block_size, 0);
-       } else {
-               sparse_file_add_data(ext4_sparse_file, aux_info.sb, 1024, 1);
-       }
+       sparse_file_add_data(ext4_sparse_file, sb, info.block_size, start_block);
 }
 
 void ext4_parse_sb_info(struct ext4_super_block *sb)

diff --git a/ext4_utils/ext4_utils.h b/ext4_utils/ext4_utils.h
index ea95446..8cc8c2c 100644 (file)
--- a/ext4_utils/ext4_utils.h
+++ b/ext4_utils/ext4_utils.h
@@ -99,6 +99,8 @@ struct ext2_group_desc {
 
 struct fs_aux_info {
        struct ext4_super_block *sb;
+       struct ext4_super_block *sb_block;
+       struct ext4_super_block *sb_zero;
        struct ext4_super_block **backup_sb;
        struct ext2_group_desc *bg_desc;
        struct block_group_info *bgs;
@@ -142,7 +144,7 @@ void ext4_fill_in_sb(int real_uuid);
 void ext4_create_resize_inode(void);
 void ext4_create_journal_inode(void);
 void ext4_update_free(void);
-void ext4_queue_sb(void);
+void ext4_queue_sb(u64 start_block, struct ext4_super_block *sb);
 u64 get_block_device_size(int fd);
 int is_block_device_fd(int fd);
 u64 get_file_size(int fd);

diff --git a/ext4_utils/make_ext4fs.c b/ext4_utils/make_ext4fs.c
index 5c9e208..5bb1872 100644 (file)
--- a/ext4_utils/make_ext4fs.c
+++ b/ext4_utils/make_ext4fs.c
@@ -503,6 +503,13 @@ int make_ext4fs_internal(int fd, const char *_directory,
        if (setjmp(setjmp_env))
                return EXIT_FAILURE; /* Handle a call to longjmp() */
 
+       info.block_device = is_block_device_fd(fd);
+
+       if (info.block_device && (sparse || gzip || crc)) {
+               fprintf(stderr, "No sparse/gzip/crc allowed for block device\n");
+               return EXIT_FAILURE;
+       }
+
        if (_mountpoint == NULL) {
                mountpoint = strdup("");
        } else {
@@ -629,8 +636,6 @@ int make_ext4fs_internal(int fd, const char *_directory,
 
        ext4_update_free();
 
-       ext4_queue_sb();
-
        if (block_list_file) {
                size_t dirlen = directory ? strlen(directory) : 0;
                struct block_allocation* p = get_saved_allocation_chain();