Enhance erofs_rebuild_load_tree() making it generate a bitmap describing
used data blocks by all regular files in given erofs image.

Signed-off-by: Jingbo Xu <[email protected]>
---
 include/erofs/rebuild.h |  3 ++-
 lib/rebuild.c           | 39 ++++++++++++++++++++++++++++++++++-----
 2 files changed, 36 insertions(+), 6 deletions(-)

diff --git a/include/erofs/rebuild.h b/include/erofs/rebuild.h
index 57c0e42..55cd856 100644
--- a/include/erofs/rebuild.h
+++ b/include/erofs/rebuild.h
@@ -21,7 +21,8 @@ struct erofs_img *erofs_get_img(const char *path);
 int erofs_add_img(const char *path);
 void erofs_cleanup_imgs(void);
 
-int erofs_rebuild_load_tree(struct erofs_inode *root, struct erofs_img *img);
+int erofs_rebuild_load_tree(struct erofs_inode *root, struct erofs_img *img,
+               unsigned long **datablk_map, unsigned long *datablks);
 
 struct erofs_dentry *erofs_rebuild_get_dentry(struct erofs_inode *pwd,
                char *path, bool aufs, bool *whout, bool *opq);
diff --git a/lib/rebuild.c b/lib/rebuild.c
index 33b539f..f641c40 100644
--- a/lib/rebuild.c
+++ b/lib/rebuild.c
@@ -11,6 +11,7 @@
 #include "erofs/dir.h"
 #include "erofs/xattr.h"
 #include "erofs/blobchunk.h"
+#include "erofs/bitops.h"
 #include "erofs/internal.h"
 
 #ifdef HAVE_LINUX_AUFS_TYPE_H
@@ -125,7 +126,7 @@ struct erofs_dentry *erofs_rebuild_get_dentry(struct 
erofs_inode *pwd,
 }
 
 static int erofs_rebuild_fill_inode_map(struct erofs_inode *inode,
-                               struct erofs_inode *vi, dev_t dev)
+               struct erofs_inode *vi, dev_t dev, unsigned long *datablk)
 {
        int ret;
        unsigned int count, unit, chunkbits, deviceid, i;
@@ -178,6 +179,9 @@ static int erofs_rebuild_fill_inode_map(struct erofs_inode 
*inode,
                        goto err;
                }
                *(void **)idx++ = chunk;
+
+               if (datablk)
+                       __set_bit(blkaddr, datablk);
                erofs_dbg("\t%s: chunk %d (deviceid %u, blkaddr %u)",
                        inode->i_srcpath, i, deviceid, blkaddr);
 
@@ -191,7 +195,7 @@ err:
 }
 
 static int erofs_rebuild_fill_inode(struct erofs_inode *inode,
-                       struct erofs_inode *vi, dev_t dev)
+               struct erofs_inode *vi, dev_t dev, unsigned long *datablk)
 {
        int ret = 0;
 
@@ -226,7 +230,7 @@ static int erofs_rebuild_fill_inode(struct erofs_inode 
*inode,
        case S_IFREG:
                inode->i_size = vi->i_size;
                if (inode->i_size)
-                       ret = erofs_rebuild_fill_inode_map(inode, vi, dev);
+                       ret = erofs_rebuild_fill_inode_map(inode, vi, dev, 
datablk);
                else
                        inode->u.i_blkaddr = NULL_ADDR;
                break;
@@ -241,6 +245,7 @@ struct erofs_rebuild_dir_context {
        struct erofs_dir_context ctx;
        struct erofs_inode *root;
        dev_t dev;
+       unsigned long *datablk;
 };
 
 static int erofs_rebuild_dirent_iter(struct erofs_dir_context *ctx)
@@ -313,7 +318,8 @@ static int erofs_rebuild_dirent_iter(struct 
erofs_dir_context *ctx)
 
                        inode->i_parent = d->inode;
                        inode->dev = rctx->dev;
-                       ret = erofs_rebuild_fill_inode(inode, &vi, rctx->dev);
+                       ret = erofs_rebuild_fill_inode(inode, &vi, rctx->dev,
+                                                      rctx->datablk);
                        if (ret)
                                goto exit_inode;
 
@@ -345,11 +351,13 @@ exit_inode:
        goto exit;
 }
 
-int erofs_rebuild_load_tree(struct erofs_inode *root, struct erofs_img *img)
+int erofs_rebuild_load_tree(struct erofs_inode *root, struct erofs_img *img,
+               unsigned long **datablk_map, unsigned long *datablks)
 {
        struct erofs_inode inode = {};
        struct erofs_sb_info *sbi = &img->sbi;
        struct erofs_rebuild_dir_context ctx;
+       unsigned long *datablk = NULL;
        int ret;
 
        erofs_dbg("Loading image %s...", img->path);
@@ -366,11 +374,27 @@ int erofs_rebuild_load_tree(struct erofs_inode *root, 
struct erofs_img *img)
                goto exit;
        }
 
+       if (datablk_map) {
+               if (sbi->extra_devices) {
+                       erofs_err("don't support scanning data blocks for extra 
devices");
+                       ret = -EOPNOTSUPP;
+                       goto exit;
+               }
+
+               datablk = calloc(BITS_TO_LONGS(sbi->total_blocks),
+                               sizeof(unsigned long));
+               if (!datablk) {
+                       ret = -ENOMEM;
+                       goto exit;
+               }
+       }
+
        inode.nid = sbi->root_nid;
        inode.sbi = sbi;
        ret = erofs_read_inode_from_disk(&inode);
        if (ret) {
                erofs_err("failed to read root inode of image %s", img->path);
+               free(datablk);
                goto exit;
        }
        inode.i_srcpath = strdup("/");
@@ -380,9 +404,14 @@ int erofs_rebuild_load_tree(struct erofs_inode *root, 
struct erofs_img *img)
                .ctx.cb = erofs_rebuild_dirent_iter,
                .root = root,
                .dev = img->dev,
+               .datablk = datablk,
        };
        ret = erofs_iterate_dir(&ctx.ctx, false);
        free(inode.i_srcpath);
+       if (datablk_map) {
+               *datablk_map = datablk;
+               *datablks = sbi->total_blocks;
+       }
 exit:
        dev_close(sbi);
        return ret;
-- 
2.19.1.6.gb485710b

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