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Commit 695b46e7 authored by Amir Goldstein's avatar Amir Goldstein Committed by Miklos Szeredi
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ovl: set i_ino to the value of st_ino for NFS export 



Eddie Horng reported that readdir of an overlayfs directory that
was exported via NFSv3 returns entries with d_type set to DT_UNKNOWN.
The reason is that while preparing the response for readdirplus, nfsd
checks inside encode_entryplus_baggage() that a child dentry's inode
number matches the value of d_ino returns by overlayfs readdir iterator.

Because the overlayfs inodes use arbitrary inode numbers that are not
correlated with the values of st_ino/d_ino, NFSv3 falls back to not
encoding d_type. Although this is an allowed behavior, we can fix it for
the case of all overlayfs layers on the same underlying filesystem.

When NFS export is enabled and d_ino is consistent with st_ino
(samefs), set the same value also to i_ino in ovl_fill_inode() for all
overlayfs inodes, nfsd readdirplus sanity checks will pass.
ovl_fill_inode() may be called from ovl_new_inode(), before real inode
was created with ino arg 0. In that case, i_ino will be updated to real
upper inode i_ino on ovl_inode_init() or ovl_inode_update().

Reported-by: default avatarEddie Horng <eddiehorng.tw@gmail.com>
Tested-by: default avatarEddie Horng <eddiehorng.tw@gmail.com>
Signed-off-by: default avatarAmir Goldstein <amir73il@gmail.com>
Fixes: 8383f174 ("ovl: wire up NFS export operations")
Cc: <stable@vger.kernel.org> #v4.16
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 3eb2ce82

fs/overlayfs/inode.c

+17 −4
Original line number Diff line number Diff line
@@ -459,8 +459,19 @@ static inline void ovl_lockdep_annotate_inode_mutex_key(struct inode *inode) 
#endif

}



static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev)

static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev,

			   unsigned long ino)

{

	/*

	 * When NFS export is enabled and d_ino is consistent with st_ino

	 * (samefs), set the same value to i_ino, because nfsd readdirplus

	 * compares d_ino values to i_ino values of child entries. When called

	 * from ovl_new_inode(), ino arg is 0, so i_ino will be updated to real

	 * upper inode i_ino on ovl_inode_init() or ovl_inode_update().

	 */

	if (inode->i_sb->s_export_op && ovl_same_sb(inode->i_sb))

		inode->i_ino = ino;

	else

		inode->i_ino = get_next_ino();

	inode->i_mode = mode;

	inode->i_flags |= S_NOCMTIME;
@@ -597,7 +608,7 @@ struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev) 


	inode = new_inode(sb);

	if (inode)

		ovl_fill_inode(inode, mode, rdev);

		ovl_fill_inode(inode, mode, rdev, 0);



	return inode;

}
@@ -710,6 +721,7 @@ struct inode *ovl_get_inode(struct super_block *sb, struct dentry *upperdentry, 
	struct inode *inode;

	bool bylower = ovl_hash_bylower(sb, upperdentry, lowerdentry, index);

	bool is_dir;

	unsigned long ino = 0;



	if (!realinode)

		realinode = d_inode(lowerdentry);
@@ -748,13 +760,14 @@ struct inode *ovl_get_inode(struct super_block *sb, struct dentry *upperdentry, 
		if (!is_dir)

			nlink = ovl_get_nlink(lowerdentry, upperdentry, nlink);

		set_nlink(inode, nlink);

		ino = key->i_ino;

	} else {

		/* Lower hardlink that will be broken on copy up */

		inode = new_inode(sb);

		if (!inode)

			goto out_nomem;

	}

	ovl_fill_inode(inode, realinode->i_mode, realinode->i_rdev);

	ovl_fill_inode(inode, realinode->i_mode, realinode->i_rdev, ino);

	ovl_inode_init(inode, upperdentry, lowerdentry);



	if (upperdentry && ovl_is_impuredir(upperdentry))

fs/overlayfs/util.c

+7 −1
Original line number Diff line number Diff line
@@ -279,12 +279,16 @@ void ovl_dentry_set_redirect(struct dentry *dentry, const char *redirect) 
void ovl_inode_init(struct inode *inode, struct dentry *upperdentry,

		    struct dentry *lowerdentry)

{

	struct inode *realinode = d_inode(upperdentry ?: lowerdentry);



	if (upperdentry)

		OVL_I(inode)->__upperdentry = upperdentry;

	if (lowerdentry)

		OVL_I(inode)->lower = igrab(d_inode(lowerdentry));



	ovl_copyattr(d_inode(upperdentry ?: lowerdentry), inode);

	ovl_copyattr(realinode, inode);

	if (!inode->i_ino)

		inode->i_ino = realinode->i_ino;

}



void ovl_inode_update(struct inode *inode, struct dentry *upperdentry)
@@ -299,6 +303,8 @@ void ovl_inode_update(struct inode *inode, struct dentry *upperdentry) 
	smp_wmb();

	OVL_I(inode)->__upperdentry = upperdentry;

	if (inode_unhashed(inode)) {

		if (!inode->i_ino)

			inode->i_ino = upperinode->i_ino;

		inode->i_private = upperinode;

		__insert_inode_hash(inode, (unsigned long) upperinode);

	}