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Commit be629c62 authored by David Woodhouse's avatar David Woodhouse
Browse files

Fix directory hardlinks from deleted directories 



When a directory is deleted, we don't take too much care about killing off
all the dirents that belong to it — on the basis that on remount, the scan
will conclude that the directory is dead anyway.

This doesn't work though, when the deleted directory contained a child
directory which was moved *out*. In the early stages of the fs build
we can then end up with an apparent hard link, with the child directory
appearing both in its true location, and as a child of the original
directory which are this stage of the mount process we don't *yet* know
is defunct.

To resolve this, take out the early special-casing of the "directories
shall not have hard links" rule in jffs2_build_inode_pass1(), and let the
normal nlink processing happen for directories as well as other inodes.

Then later in the build process we can set ic->pino_nlink to the parent
inode#, as is required for directories during normal operaton, instead
of the nlink. And complain only *then* about hard links which are still
in evidence even after killing off all the unreachable paths.

Reported-by: default avatarLiu Song <liu.song11@zte.com.cn>
Signed-off-by: default avatarDavid Woodhouse <David.Woodhouse@intel.com>
Cc: stable@vger.kernel.org
parent 49e91e70

fs/jffs2/build.c

+57 −18
Original line number Diff line number Diff line
@@ -50,7 +50,8 @@ next_inode(int *i, struct jffs2_inode_cache *ic, struct jffs2_sb_info *c) 




static void jffs2_build_inode_pass1(struct jffs2_sb_info *c,

				    struct jffs2_inode_cache *ic)

				    struct jffs2_inode_cache *ic,

				    int *dir_hardlinks)

{

	struct jffs2_full_dirent *fd;
@@ -69,19 +70,21 @@ static void jffs2_build_inode_pass1(struct jffs2_sb_info *c, 
			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) {

			if (child_ic->pino_nlink) {

				JFFS2_ERROR("child dir \"%s\" (ino #%u) of dir ino #%u appears to be a hard link\n",

					    fd->name, fd->ino, ic->ino);

				/* TODO: What do we do about it? */

			} else {

				child_ic->pino_nlink = ic->ino;

			child_ic->flags |= INO_FLAGS_IS_DIR;

			if (child_ic->pino_nlink > 1)

				*dir_hardlinks = 1;

		}

		} else

			child_ic->pino_nlink++;



		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 */
@@ -95,8 +98,7 @@ static void jffs2_build_inode_pass1(struct jffs2_sb_info *c, 
*/

static int jffs2_build_filesystem(struct jffs2_sb_info *c)

{

	int ret;

	int i;

	int ret, i, dir_hardlinks = 0;

	struct jffs2_inode_cache *ic;

	struct jffs2_full_dirent *fd;

	struct jffs2_full_dirent *dead_fds = NULL;
@@ -120,7 +122,7 @@ static int jffs2_build_filesystem(struct jffs2_sb_info *c) 
	/* 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);

			jffs2_build_inode_pass1(c, ic, &dir_hardlinks);

			cond_resched();

		}

	}
@@ -156,6 +158,20 @@ static int jffs2_build_filesystem(struct jffs2_sb_info *c) 
	}



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



	if (dir_hardlinks) {

		/* If we detected directory hardlinks earlier, *hopefully*

		 * they are gone now because some of the links were from

		 * dead directories which still had some old dirents lying

		 * around and not yet garbage-collected, but which have

		 * been discarded above. So clear the pino_nlink field

		 * in each directory, so that the final scan below can

		 * print appropriate warnings. */

		for_each_inode(i, c, ic) {

			if (ic->flags & INO_FLAGS_IS_DIR)

				ic->pino_nlink = 0;

		}

	}

	dbg_fsbuild("freeing temporary data structures\n");



	/* Finally, we can scan again and free the dirent structs */
@@ -163,6 +179,33 @@ static int jffs2_build_filesystem(struct jffs2_sb_info *c) 
		while(ic->scan_dents) {

			fd = ic->scan_dents;

			ic->scan_dents = fd->next;

			/* We do use the pino_nlink field to count nlink of

			 * directories during fs build, so set it to the

			 * parent ino# now. Now that there's hopefully only

			 * one. */

			if (fd->type == DT_DIR) {

				if (!fd->ic) {

					/* We'll have complained about it and marked the coresponding

					   raw node obsolete already. Just skip it. */

					continue;

				}



				/* We *have* to have set this in jffs2_build_inode_pass1() */

				BUG_ON(!(fd->ic->flags & INO_FLAGS_IS_DIR));



				/* We clear ic->pino_nlink ∀ directories' ic *only* if dir_hardlinks

				 * is set. Otherwise, we know this should never trigger anyway, so

				 * we don't do the check. And ic->pino_nlink still contains the nlink

				 * value (which is 1). */

				if (dir_hardlinks && fd->ic->pino_nlink) {

					JFFS2_ERROR("child dir \"%s\" (ino #%u) of dir ino #%u is also hard linked from dir ino #%u\n",

						    fd->name, fd->ino, ic->ino, fd->ic->pino_nlink);

					/* Should we unlink it from its previous parent? */

				}



				/* For directories, ic->pino_nlink holds that parent inode # */

				fd->ic->pino_nlink = ic->ino;

			}

			jffs2_free_full_dirent(fd);

		}

		ic->scan_dents = NULL;
@@ -241,10 +284,6 @@ static void jffs2_build_remove_unlinked_inode(struct jffs2_sb_info *c, 


			/* Reduce nlink of the child. If it's now zero, stick it on the

			   dead_fds list to be cleaned up later. Else just free the fd */



			if (fd->type == DT_DIR)

				child_ic->pino_nlink = 0;

			else

			child_ic->pino_nlink--;



			if (!child_ic->pino_nlink) {

fs/jffs2/nodelist.h

+5 −1
Original line number Diff line number Diff line
@@ -194,6 +194,7 @@ struct jffs2_inode_cache { 
#define INO_STATE_CLEARING	6	/* In clear_inode() */



#define INO_FLAGS_XATTR_CHECKED	0x01	/* has no duplicate xattr_ref */

#define INO_FLAGS_IS_DIR	0x02	/* is a directory */



#define RAWNODE_CLASS_INODE_CACHE	0

#define RAWNODE_CLASS_XATTR_DATUM	1
@@ -249,7 +250,10 @@ struct jffs2_readinode_info 


struct jffs2_full_dirent

{

	union {

		struct jffs2_raw_node_ref *raw;

		struct jffs2_inode_cache *ic; /* Just during part of build */

	};

	struct jffs2_full_dirent *next;

	uint32_t version;

	uint32_t ino; /* == zero for unlink */