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ovl: fold copy-up helpers into callers
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Now that the workdir and tmpfile copy up modes have been untagled, the
functions become simple enough that the helpers can be folded into the
callers.

Add new helpers where there is any duplication remaining: preparing creds
for creating the object.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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Miklos Szeredi committed Oct 26, 2018
1 parent b10cdcd commit 6b52243
Showing 1 changed file with 67 additions and 108 deletions.
175 changes: 67 additions & 108 deletions fs/overlayfs/copy_up.c
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Original file line number Diff line number Diff line change
Expand Up @@ -490,59 +490,32 @@ static int ovl_copy_up_inode(struct ovl_copy_up_ctx *c, struct dentry *temp)
return err;
}

static struct dentry *ovl_get_workdir_temp(struct ovl_copy_up_ctx *c)
struct ovl_cu_creds {
const struct cred *old;
struct cred *new;
};

static int ovl_prep_cu_creds(struct dentry *dentry, struct ovl_cu_creds *cc)
{
int err;
struct dentry *temp;
const struct cred *old_creds = NULL;
struct cred *new_creds = NULL;
struct ovl_cattr cattr = {
/* Can't properly set mode on creation because of the umask */
.mode = c->stat.mode & S_IFMT,
.rdev = c->stat.rdev,
.link = c->link
};

err = security_inode_copy_up(c->dentry, &new_creds);
cc->old = cc->new = NULL;
err = security_inode_copy_up(dentry, &cc->new);
if (err < 0)
return ERR_PTR(err);

if (new_creds)
old_creds = override_creds(new_creds);

temp = ovl_create_temp(c->workdir, &cattr);
return err;

if (new_creds) {
revert_creds(old_creds);
put_cred(new_creds);
}
if (cc->new)
cc->old = override_creds(cc->new);

return temp;
return 0;
}

/*
* Move temp file from workdir into place on upper dir.
* Used when copying up directories and when upper fs doesn't support O_TMPFILE.
*
* Caller must hold ovl_lock_rename_workdir().
*/
static int ovl_rename_temp(struct ovl_copy_up_ctx *c, struct dentry *temp,
struct dentry **newdentry)
static void ovl_revert_cu_creds(struct ovl_cu_creds *cc)
{
int err;
struct dentry *upper;
struct inode *udir = d_inode(c->destdir);

upper = lookup_one_len(c->destname.name, c->destdir, c->destname.len);
if (IS_ERR(upper))
return PTR_ERR(upper);

err = ovl_do_rename(d_inode(c->workdir), temp, udir, upper, 0);
if (!err)
*newdentry = dget(temp);
dput(upper);

return err;
if (cc->new) {
revert_creds(cc->old);
put_cred(cc->new);
}
}

/*
Expand All @@ -552,15 +525,28 @@ static int ovl_rename_temp(struct ovl_copy_up_ctx *c, struct dentry *temp,
static int ovl_copy_up_workdir(struct ovl_copy_up_ctx *c)
{
struct inode *inode;
struct dentry *newdentry = NULL;
struct dentry *temp;
struct inode *udir = d_inode(c->destdir), *wdir = d_inode(c->workdir);
struct dentry *temp, *upper;
struct ovl_cu_creds cc;
int err;
struct ovl_cattr cattr = {
/* Can't properly set mode on creation because of the umask */
.mode = c->stat.mode & S_IFMT,
.rdev = c->stat.rdev,
.link = c->link
};

err = ovl_lock_rename_workdir(c->workdir, c->destdir);
if (err)
return err;

temp = ovl_get_workdir_temp(c);
err = ovl_prep_cu_creds(c->dentry, &cc);
if (err)
goto unlock;

temp = ovl_create_temp(c->workdir, &cattr);
ovl_revert_cu_creds(&cc);

err = PTR_ERR(temp);
if (IS_ERR(temp))
goto unlock;
Expand All @@ -575,102 +561,75 @@ static int ovl_copy_up_workdir(struct ovl_copy_up_ctx *c)
goto cleanup;
}

err = ovl_rename_temp(c, temp, &newdentry);
upper = lookup_one_len(c->destname.name, c->destdir, c->destname.len);
err = PTR_ERR(upper);
if (IS_ERR(upper))
goto cleanup;

err = ovl_do_rename(wdir, temp, udir, upper, 0);
dput(upper);
if (err)
goto cleanup;

if (!c->metacopy)
ovl_set_upperdata(d_inode(c->dentry));
inode = d_inode(c->dentry);
ovl_inode_update(inode, newdentry);
ovl_inode_update(inode, temp);
if (S_ISDIR(inode->i_mode))
ovl_set_flag(OVL_WHITEOUTS, inode);
out_dput:
dput(temp);
unlock:
unlock_rename(c->workdir, c->destdir);

return err;

cleanup:
ovl_cleanup(d_inode(c->workdir), temp);
goto out_dput;
ovl_cleanup(wdir, temp);
dput(temp);
goto unlock;
}

static struct dentry *ovl_get_tmpfile(struct ovl_copy_up_ctx *c)
/* Copyup using O_TMPFILE which does not require cross dir locking */
static int ovl_copy_up_tmpfile(struct ovl_copy_up_ctx *c)
{
struct inode *udir = d_inode(c->destdir);
struct dentry *temp, *upper;
struct ovl_cu_creds cc;
int err;
struct dentry *temp;
const struct cred *old_creds = NULL;
struct cred *new_creds = NULL;

err = security_inode_copy_up(c->dentry, &new_creds);
if (err < 0)
return ERR_PTR(err);

if (new_creds)
old_creds = override_creds(new_creds);
err = ovl_prep_cu_creds(c->dentry, &cc);
if (err)
return err;

temp = ovl_do_tmpfile(c->workdir, c->stat.mode);
ovl_revert_cu_creds(&cc);

if (new_creds) {
revert_creds(old_creds);
put_cred(new_creds);
}

return temp;
}
if (IS_ERR(temp))
return PTR_ERR(temp);

/* Link O_TMPFILE into place on upper dir */
static int ovl_link_tmpfile(struct ovl_copy_up_ctx *c, struct dentry *temp,
struct dentry **newdentry)
{
int err;
struct dentry *upper;
struct inode *udir = d_inode(c->destdir);
err = ovl_copy_up_inode(c, temp);
if (err)
goto out_dput;

inode_lock_nested(udir, I_MUTEX_PARENT);

upper = lookup_one_len(c->destname.name, c->destdir, c->destname.len);
err = PTR_ERR(upper);
if (IS_ERR(upper))
goto unlock;

err = ovl_do_link(temp, udir, upper);
if (!err)
*newdentry = dget(upper);
dput(upper);

unlock:
if (!IS_ERR(upper)) {
err = ovl_do_link(temp, udir, upper);
dput(upper);
}
inode_unlock(udir);

return err;
}

/* Copyup using O_TMPFILE which does not require cross dir locking */
static int ovl_copy_up_tmpfile(struct ovl_copy_up_ctx *c)
{
struct dentry *newdentry = NULL;
struct dentry *temp;
int err;

temp = ovl_get_tmpfile(c);
if (IS_ERR(temp))
return PTR_ERR(temp);

err = ovl_copy_up_inode(c, temp);
if (err)
goto out;

err = ovl_link_tmpfile(c, temp, &newdentry);
if (err)
goto out;
goto out_dput;

if (!c->metacopy)
ovl_set_upperdata(d_inode(c->dentry));
ovl_inode_update(d_inode(c->dentry), newdentry);
ovl_inode_update(d_inode(c->dentry), temp);

out:
return 0;

out_dput:
dput(temp);
return err;
}
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