fs/jffs2/build.c

Source file repositories/reference/linux-study-clean/fs/jffs2/build.c

File Facts

System
Linux kernel
Corpus path
fs/jffs2/build.c
Extension
.c
Size
12926 bytes
Lines
435
Domain
Core OS
Bucket
VFS And Filesystem Core
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

if (!child_ic) {
			dbg_fsbuild("child \"%s\" (ino #%u) of dir ino #%u doesn't exist!\n",
				  fd->name, fd->ino, ic->ino);
			jffs2_mark_node_obsolete(c, fd->raw);
			/* Clear the ic/raw union so it doesn't cause problems later. */
			fd->ic = NULL;
			continue;
		}

		/* From this point, fd->raw is no longer used so we can set fd->ic */
		fd->ic = child_ic;
		child_ic->pino_nlink++;
		/* If we appear (at this stage) to have hard-linked directories,
		 * set a flag to trigger a scan later */
		if (fd->type == DT_DIR) {
			child_ic->flags |= INO_FLAGS_IS_DIR;
			if (child_ic->pino_nlink > 1)
				*dir_hardlinks = 1;
		}

		dbg_fsbuild("increased nlink for child \"%s\" (ino #%u)\n", fd->name, fd->ino);
		/* Can't free scan_dents so far. We might need them in pass 2 */
	}
}

/* Scan plan:
 - Scan physical nodes. Build map of inodes/dirents. Allocate inocaches as we go
 - Scan directory tree from top down, setting nlink in inocaches
 - Scan inocaches for inodes with nlink==0
*/
static int jffs2_build_filesystem(struct jffs2_sb_info *c)
{
	int ret, i, dir_hardlinks = 0;
	struct jffs2_inode_cache *ic;
	struct jffs2_full_dirent *fd;
	struct jffs2_full_dirent *dead_fds = NULL;

	dbg_fsbuild("build FS data structures\n");

	/* First, scan the medium and build all the inode caches with
	   lists of physical nodes */

	c->flags |= JFFS2_SB_FLAG_SCANNING;
	ret = jffs2_scan_medium(c);
	c->flags &= ~JFFS2_SB_FLAG_SCANNING;
	if (ret)
		goto exit;

	dbg_fsbuild("scanned flash completely\n");
	jffs2_dbg_dump_block_lists_nolock(c);

	dbg_fsbuild("pass 1 starting\n");
	c->flags |= JFFS2_SB_FLAG_BUILDING;
	/* Now scan the directory tree, increasing nlink according to every dirent found. */
	for_each_inode(i, c, ic) {
		if (ic->scan_dents) {
			jffs2_build_inode_pass1(c, ic, &dir_hardlinks);
			cond_resched();
		}
	}

	dbg_fsbuild("pass 1 complete\n");

	/* Next, scan for inodes with nlink == 0 and remove them. If
	   they were directories, then decrement the nlink of their
	   children too, and repeat the scan. As that's going to be
	   a fairly uncommon occurrence, it's not so evil to do it this
	   way. Recursion bad. */
	dbg_fsbuild("pass 2 starting\n");

	for_each_inode(i, c, ic) {
		if (ic->pino_nlink)
			continue;

		jffs2_build_remove_unlinked_inode(c, ic, &dead_fds);
		cond_resched();
	}

	dbg_fsbuild("pass 2a starting\n");

	while (dead_fds) {
		fd = dead_fds;
		dead_fds = fd->next;

		ic = jffs2_get_ino_cache(c, fd->ino);

		if (ic)
			jffs2_build_remove_unlinked_inode(c, ic, &dead_fds);
		jffs2_free_full_dirent(fd);
	}

Annotation

Implementation Notes