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ovl: set i_ino to the value of st_ino for NFS export

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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: Eddie Horng <eddiehorng.tw@gmail.com>
Tested-by: Eddie Horng <eddiehorng.tw@gmail.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Fixes: 8383f17488 ("ovl: wire up NFS export operations")
Cc: <stable@vger.kernel.org> #v4.16
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Amir Goldstein 2018-03-15 23:39:01 +02:00 committed by Miklos Szeredi
parent 3eb2ce825e
commit 695b46e76b
2 changed files with 24 additions and 5 deletions
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21
fs/overlayfs/inode.c
View File

@ -459,9 +459,20 @@ 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)
{
inode->i_ino = get_next_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;
#ifdef CONFIG_FS_POSIX_ACL
@ -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))

8
fs/overlayfs/util.c
View File

@ -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);
}