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ovl: untangle copy up call chain
In an attempt to dedup ~100 LOC, we ended up creating a tangled call chain, whose branches merge and diverge in several points according to the immutable c->tmpfile copy up mode. This call chain was hard to analyse for locking correctness because the locking requirements for the c->tmpfile flow were very different from the locking requirements for the !c->tmpfile flow (i.e. directory vs. regulare file copy up). Split the copy up helpers of the c->tmpfile flow from those of the !c->tmpfile (i.e. workdir) flow and remove the c->tmpfile mode from copy up context. Suggested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Amir Goldstein <amir73il@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This commit is contained in:
Amir Goldstein
Miklos Szeredi
parent
007ea44892
commit
b10cdcdc20
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@ -395,7 +395,6 @@ struct ovl_copy_up_ctx {
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struct dentry *destdir;
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struct qstr destname;
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struct dentry *workdir;
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bool tmpfile;
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bool origin;
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bool indexed;
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bool metacopy;
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@ -440,62 +439,6 @@ static int ovl_link_up(struct ovl_copy_up_ctx *c)
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return err;
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}
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static int ovl_install_temp(struct ovl_copy_up_ctx *c, struct dentry *temp,
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struct dentry **newdentry)
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{
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int err;
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struct dentry *upper;
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struct inode *udir = d_inode(c->destdir);
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upper = lookup_one_len(c->destname.name, c->destdir, c->destname.len);
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if (IS_ERR(upper))
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return PTR_ERR(upper);
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if (c->tmpfile)
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err = ovl_do_link(temp, udir, upper);
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else
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err = ovl_do_rename(d_inode(c->workdir), temp, udir, upper, 0);
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if (!err)
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*newdentry = dget(c->tmpfile ? upper : temp);
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dput(upper);
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return err;
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}
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static struct dentry *ovl_get_tmpfile(struct ovl_copy_up_ctx *c)
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{
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int err;
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struct dentry *temp;
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const struct cred *old_creds = NULL;
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struct cred *new_creds = NULL;
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struct ovl_cattr cattr = {
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/* Can't properly set mode on creation because of the umask */
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.mode = c->stat.mode & S_IFMT,
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.rdev = c->stat.rdev,
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.link = c->link
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};
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err = security_inode_copy_up(c->dentry, &new_creds);
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if (err < 0)
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return ERR_PTR(err);
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if (new_creds)
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old_creds = override_creds(new_creds);
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if (c->tmpfile)
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temp = ovl_do_tmpfile(c->workdir, c->stat.mode);
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else
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temp = ovl_create_temp(c->workdir, &cattr);
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if (new_creds) {
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revert_creds(old_creds);
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put_cred(new_creds);
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}
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return temp;
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}
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static int ovl_copy_up_inode(struct ovl_copy_up_ctx *c, struct dentry *temp)
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{
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int err;
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@ -547,14 +490,170 @@ static int ovl_copy_up_inode(struct ovl_copy_up_ctx *c, struct dentry *temp)
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return err;
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}
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static int ovl_copy_up_locked(struct ovl_copy_up_ctx *c)
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static struct dentry *ovl_get_workdir_temp(struct ovl_copy_up_ctx *c)
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{
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int err;
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struct dentry *temp;
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const struct cred *old_creds = NULL;
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struct cred *new_creds = NULL;
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struct ovl_cattr cattr = {
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/* Can't properly set mode on creation because of the umask */
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.mode = c->stat.mode & S_IFMT,
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.rdev = c->stat.rdev,
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.link = c->link
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};
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err = security_inode_copy_up(c->dentry, &new_creds);
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if (err < 0)
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return ERR_PTR(err);
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if (new_creds)
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old_creds = override_creds(new_creds);
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temp = ovl_create_temp(c->workdir, &cattr);
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if (new_creds) {
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revert_creds(old_creds);
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put_cred(new_creds);
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}
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return temp;
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}
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/*
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* Move temp file from workdir into place on upper dir.
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* Used when copying up directories and when upper fs doesn't support O_TMPFILE.
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*
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* Caller must hold ovl_lock_rename_workdir().
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*/
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static int ovl_rename_temp(struct ovl_copy_up_ctx *c, struct dentry *temp,
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struct dentry **newdentry)
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{
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int err;
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struct dentry *upper;
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struct inode *udir = d_inode(c->destdir);
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upper = lookup_one_len(c->destname.name, c->destdir, c->destname.len);
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if (IS_ERR(upper))
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return PTR_ERR(upper);
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err = ovl_do_rename(d_inode(c->workdir), temp, udir, upper, 0);
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if (!err)
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*newdentry = dget(temp);
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dput(upper);
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return err;
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}
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/*
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* Copyup using workdir to prepare temp file. Used when copying up directories,
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* special files or when upper fs doesn't support O_TMPFILE.
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*/
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static int ovl_copy_up_workdir(struct ovl_copy_up_ctx *c)
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{
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struct inode *udir = c->destdir->d_inode;
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struct inode *inode;
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struct dentry *newdentry = NULL;
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struct dentry *temp;
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int err;
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err = ovl_lock_rename_workdir(c->workdir, c->destdir);
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if (err)
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return err;
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temp = ovl_get_workdir_temp(c);
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err = PTR_ERR(temp);
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if (IS_ERR(temp))
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goto unlock;
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err = ovl_copy_up_inode(c, temp);
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if (err)
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goto cleanup;
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if (S_ISDIR(c->stat.mode) && c->indexed) {
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err = ovl_create_index(c->dentry, c->lowerpath.dentry, temp);
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if (err)
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goto cleanup;
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}
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err = ovl_rename_temp(c, temp, &newdentry);
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if (err)
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goto cleanup;
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if (!c->metacopy)
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ovl_set_upperdata(d_inode(c->dentry));
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inode = d_inode(c->dentry);
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ovl_inode_update(inode, newdentry);
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if (S_ISDIR(inode->i_mode))
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ovl_set_flag(OVL_WHITEOUTS, inode);
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out_dput:
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dput(temp);
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unlock:
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unlock_rename(c->workdir, c->destdir);
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return err;
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cleanup:
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ovl_cleanup(d_inode(c->workdir), temp);
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goto out_dput;
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}
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static struct dentry *ovl_get_tmpfile(struct ovl_copy_up_ctx *c)
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{
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int err;
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struct dentry *temp;
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const struct cred *old_creds = NULL;
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struct cred *new_creds = NULL;
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err = security_inode_copy_up(c->dentry, &new_creds);
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if (err < 0)
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return ERR_PTR(err);
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if (new_creds)
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old_creds = override_creds(new_creds);
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temp = ovl_do_tmpfile(c->workdir, c->stat.mode);
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if (new_creds) {
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revert_creds(old_creds);
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put_cred(new_creds);
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}
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return temp;
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}
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/* Link O_TMPFILE into place on upper dir */
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static int ovl_link_tmpfile(struct ovl_copy_up_ctx *c, struct dentry *temp,
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struct dentry **newdentry)
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{
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int err;
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struct dentry *upper;
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struct inode *udir = d_inode(c->destdir);
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inode_lock_nested(udir, I_MUTEX_PARENT);
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upper = lookup_one_len(c->destname.name, c->destdir, c->destname.len);
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err = PTR_ERR(upper);
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if (IS_ERR(upper))
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goto unlock;
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err = ovl_do_link(temp, udir, upper);
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if (!err)
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*newdentry = dget(upper);
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dput(upper);
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unlock:
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inode_unlock(udir);
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return err;
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}
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/* Copyup using O_TMPFILE which does not require cross dir locking */
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static int ovl_copy_up_tmpfile(struct ovl_copy_up_ctx *c)
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{
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struct dentry *newdentry = NULL;
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struct dentry *temp;
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int err;
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temp = ovl_get_tmpfile(c);
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if (IS_ERR(temp))
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return PTR_ERR(temp);
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@ -563,35 +662,17 @@ static int ovl_copy_up_locked(struct ovl_copy_up_ctx *c)
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if (err)
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goto out;
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if (S_ISDIR(c->stat.mode) && c->indexed) {
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err = ovl_create_index(c->dentry, c->lowerpath.dentry, temp);
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if (err)
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goto out;
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}
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if (c->tmpfile) {
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inode_lock_nested(udir, I_MUTEX_PARENT);
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err = ovl_install_temp(c, temp, &newdentry);
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inode_unlock(udir);
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} else {
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err = ovl_install_temp(c, temp, &newdentry);
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}
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err = ovl_link_tmpfile(c, temp, &newdentry);
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if (err)
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goto out;
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if (!c->metacopy)
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ovl_set_upperdata(d_inode(c->dentry));
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inode = d_inode(c->dentry);
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ovl_inode_update(inode, newdentry);
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if (S_ISDIR(inode->i_mode))
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ovl_set_flag(OVL_WHITEOUTS, inode);
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ovl_inode_update(d_inode(c->dentry), newdentry);
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out:
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if (err && !c->tmpfile)
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ovl_cleanup(d_inode(c->workdir), temp);
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dput(temp);
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return err;
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}
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/*
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@ -645,18 +726,10 @@ static int ovl_do_copy_up(struct ovl_copy_up_ctx *c)
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}
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/* Should we copyup with O_TMPFILE or with workdir? */
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if (S_ISREG(c->stat.mode) && ofs->tmpfile) {
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c->tmpfile = true;
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err = ovl_copy_up_locked(c);
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} else {
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err = ovl_lock_rename_workdir(c->workdir, c->destdir);
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if (!err) {
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err = ovl_copy_up_locked(c);
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unlock_rename(c->workdir, c->destdir);
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}
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}
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if (S_ISREG(c->stat.mode) && ofs->tmpfile)
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err = ovl_copy_up_tmpfile(c);
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else
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err = ovl_copy_up_workdir(c);
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if (err)
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goto out;
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