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ovl: decode indexed non-dir file handles

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Decoding an indexed non-dir file handle is similar to decoding a lower
non-dir file handle, but additionally, we lookup the file handle in index
dir by name to find the real upper inode.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Amir Goldstein 2018-01-19 21:36:20 +02:00 committed by Miklos Szeredi
parent f941866fc4
commit f71bd9cfb6
1 changed files with 46 additions and 25 deletions
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71
fs/overlayfs/export.c
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@ -163,27 +163,32 @@ static int ovl_encode_inode_fh(struct inode *inode, u32 *fid, int *max_len,
}
/*
* Find or instantiate an overlay dentry from real dentries.
* Find or instantiate an overlay dentry from real dentries and index.
*/
static struct dentry *ovl_obtain_alias(struct super_block *sb,
struct dentry *upper,
struct ovl_path *lowerpath)
struct dentry *upper_alias,
struct ovl_path *lowerpath,
struct dentry *index)
{
struct dentry *lower = lowerpath ? lowerpath->dentry : NULL;
struct dentry *upper = upper_alias ?: index;
struct dentry *dentry;
struct inode *inode;
struct ovl_entry *oe;
/* TODO: obtain an indexed non-dir upper with origin */
if (lower && (upper || d_is_dir(lower)))
/* We get overlay directory dentries with ovl_lookup_real() */
if (d_is_dir(upper ?: lower))
return ERR_PTR(-EIO);
inode = ovl_get_inode(sb, dget(upper), lower, NULL, !!lower);
inode = ovl_get_inode(sb, dget(upper), lower, index, !!lower);
if (IS_ERR(inode)) {
dput(upper);
return ERR_CAST(inode);
}
if (index)
ovl_set_flag(OVL_INDEX, inode);
dentry = d_find_any_alias(inode);
if (!dentry) {
dentry = d_alloc_anon(inode->i_sb);
@ -198,7 +203,7 @@ static struct dentry *ovl_obtain_alias(struct super_block *sb,
oe->lowerstack->layer = lowerpath->layer;
}
dentry->d_fsdata = oe;
if (upper)
if (upper_alias)
ovl_dentry_set_upper_alias(dentry);
}
@ -377,33 +382,28 @@ fail:
}
/*
* Get an overlay dentry from upper/lower real dentries.
* Get an overlay dentry from upper/lower real dentries and index.
*/
static struct dentry *ovl_get_dentry(struct super_block *sb,
struct dentry *upper,
struct ovl_path *lowerpath)
struct ovl_path *lowerpath,
struct dentry *index)
{
struct ovl_fs *ofs = sb->s_fs_info;
struct ovl_layer upper_layer = { .mnt = ofs->upper_mnt };
struct dentry *real = upper ?: (index ?: lowerpath->dentry);
/*
* Obtain a disconnected overlay dentry from a disconnected non-dir
* real lower dentry.
* Obtain a disconnected overlay dentry from a non-dir real dentry
* and index.
*/
if (!upper && !d_is_dir(lowerpath->dentry))
return ovl_obtain_alias(sb, NULL, lowerpath);
if (!d_is_dir(real))
return ovl_obtain_alias(sb, upper, lowerpath, index);
/* TODO: lookup connected dir from real lower dir */
if (!upper)
return ERR_PTR(-EACCES);
/*
* Obtain a disconnected overlay dentry from a non-dir real upper
* dentry.
*/
if (!d_is_dir(upper))
return ovl_obtain_alias(sb, upper, NULL);
/* Removed empty directory? */
if ((upper->d_flags & DCACHE_DISCONNECTED) || d_unhashed(upper))
return ERR_PTR(-ENOENT);
@ -429,7 +429,7 @@ static struct dentry *ovl_upper_fh_to_d(struct super_block *sb,
if (IS_ERR_OR_NULL(upper))
return upper;
dentry = ovl_get_dentry(sb, upper, NULL);
dentry = ovl_get_dentry(sb, upper, NULL, NULL);
dput(upper);
return dentry;
@ -442,16 +442,37 @@ static struct dentry *ovl_lower_fh_to_d(struct super_block *sb,
struct ovl_path origin = { };
struct ovl_path *stack = &origin;
struct dentry *dentry = NULL;
struct dentry *index = NULL;
int err;
/* First lookup indexed upper by fh */
if (ofs->indexdir) {
index = ovl_get_index_fh(ofs, fh);
err = PTR_ERR(index);
if (IS_ERR(index))
return ERR_PTR(err);
}
/* Then lookup origin by fh */
err = ovl_check_origin_fh(ofs, fh, NULL, &stack);
if (err)
return ERR_PTR(err);
if (err) {
goto out_err;
} else if (index) {
err = ovl_verify_origin(index, origin.dentry, false);
if (err)
goto out_err;
}
dentry = ovl_get_dentry(sb, NULL, &origin);
dentry = ovl_get_dentry(sb, NULL, &origin, index);
out:
dput(origin.dentry);
dput(index);
return dentry;
out_err:
dentry = ERR_PTR(err);
goto out;
}
static struct dentry *ovl_fh_to_dentry(struct super_block *sb, struct fid *fid,