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Commit adbf4f7e authored by Amir Goldstein's avatar Amir Goldstein Committed by Miklos Szeredi
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ovl: consistent d_ino for non-samefs with xino 



When overlay layers are not all on the same fs, but all inode numbers
of underlying fs do not use the high 'xino' bits, overlay st_ino values
are constant and persistent.

In that case, relax non-samefs constraint for consistent d_ino and always
iterate non-merge dir using ovl_fill_real() actor so we can remap lower
inode numbers to unique lower fs range.

Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 12574a9f

fs/overlayfs/readdir.c

+39 −6
Original line number Diff line number Diff line
@@ -120,6 +120,10 @@ static bool ovl_calc_d_ino(struct ovl_readdir_data *rdd, 
	if (!rdd->dentry)

		return false;



	/* Always recalc d_ino when remapping lower inode numbers */

	if (ovl_xino_bits(rdd->dentry->d_sb))

		return true;



	/* Always recalc d_ino for parent */

	if (strcmp(p->name, "..") == 0)

		return true;
@@ -435,6 +439,19 @@ static struct ovl_dir_cache *ovl_cache_get(struct dentry *dentry) 
	return cache;

}



/* Map inode number to lower fs unique range */

static u64 ovl_remap_lower_ino(u64 ino, int xinobits, int fsid,

			       const char *name, int namelen)

{

	if (ino >> (64 - xinobits)) {

		pr_warn_ratelimited("overlayfs: d_ino too big (%.*s, ino=%llu, xinobits=%d)\n",

				    namelen, name, ino, xinobits);

		return ino;

	}



	return ino | ((u64)fsid) << (64 - xinobits);

}



/*

 * Set d_ino for upper entries. Non-upper entries should always report

 * the uppermost real inode ino and should not call this function.
@@ -452,9 +469,10 @@ static int ovl_cache_update_ino(struct path *path, struct ovl_cache_entry *p) 
	struct dentry *this = NULL;

	enum ovl_path_type type;

	u64 ino = p->real_ino;

	int xinobits = ovl_xino_bits(dir->d_sb);

	int err = 0;



	if (!ovl_same_sb(dir->d_sb))

	if (!ovl_same_sb(dir->d_sb) && !xinobits)

		goto out;



	if (p->name[0] == '.') {
@@ -491,6 +509,10 @@ static int ovl_cache_update_ino(struct path *path, struct ovl_cache_entry *p) 


		WARN_ON_ONCE(dir->d_sb->s_dev != stat.dev);

		ino = stat.ino;

	} else if (xinobits && !OVL_TYPE_UPPER(type)) {

		ino = ovl_remap_lower_ino(ino, xinobits,

					  ovl_layer_lower(this)->fsid,

					  p->name, p->len);

	}



out:
@@ -618,6 +640,8 @@ struct ovl_readdir_translate { 
	struct ovl_dir_cache *cache;

	struct dir_context ctx;

	u64 parent_ino;

	int fsid;

	int xinobits;

};



static int ovl_fill_real(struct dir_context *ctx, const char *name,
@@ -628,14 +652,17 @@ static int ovl_fill_real(struct dir_context *ctx, const char *name, 
		container_of(ctx, struct ovl_readdir_translate, ctx);

	struct dir_context *orig_ctx = rdt->orig_ctx;



	if (rdt->parent_ino && strcmp(name, "..") == 0)

	if (rdt->parent_ino && strcmp(name, "..") == 0) {

		ino = rdt->parent_ino;

	else if (rdt->cache) {

	} else if (rdt->cache) {

		struct ovl_cache_entry *p;



		p = ovl_cache_entry_find(&rdt->cache->root, name, namelen);

		if (p)

			ino = p->ino;

	} else if (rdt->xinobits) {

		ino = ovl_remap_lower_ino(ino, rdt->xinobits, rdt->fsid,

					  name, namelen);

	}



	return orig_ctx->actor(orig_ctx, name, namelen, offset, ino, d_type);
@@ -646,11 +673,16 @@ static int ovl_iterate_real(struct file *file, struct dir_context *ctx) 
	int err;

	struct ovl_dir_file *od = file->private_data;

	struct dentry *dir = file->f_path.dentry;

	struct ovl_layer *lower_layer = ovl_layer_lower(dir);

	struct ovl_readdir_translate rdt = {

		.ctx.actor = ovl_fill_real,

		.orig_ctx = ctx,

		.xinobits = ovl_xino_bits(dir->d_sb),

	};



	if (rdt.xinobits && lower_layer)

		rdt.fsid = lower_layer->fsid;



	if (OVL_TYPE_MERGE(ovl_path_type(dir->d_parent))) {

		struct kstat stat;

		struct path statpath = file->f_path;
@@ -693,9 +725,10 @@ static int ovl_iterate(struct file *file, struct dir_context *ctx) 
		 * dir is impure then need to adjust d_ino for copied up

		 * entries.

		 */

		if (ovl_same_sb(dentry->d_sb) &&

		if (ovl_xino_bits(dentry->d_sb) ||

		    (ovl_same_sb(dentry->d_sb) &&

		     (ovl_test_flag(OVL_IMPURE, d_inode(dentry)) ||

		     OVL_TYPE_MERGE(ovl_path_type(dentry->d_parent)))) {

		      OVL_TYPE_MERGE(ovl_path_type(dentry->d_parent))))) {

			return ovl_iterate_real(file, ctx);

		}

		return iterate_dir(od->realfile, ctx);