2024-03-15 16:55:19

by Jeff Layton

Subject: [PATCH RFC 03/24] vfs: add try_break_deleg calls for parents to vfs_{link,rename,unlink}

In order to add directory delegation support, we need to break
delegations on the parent whenever there is going to be a change in the
directory.

vfs_link, vfs_unlink, and vfs_rename all have existing delegation break
handling for the children in the rename. Add the necessary calls for
breaking delegations in the parent(s) as well.

Signed-off-by: Jeff Layton <[email protected]>
---
fs/namei.c | 20 +++++++++++++++++---
1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 9342fa6a38c2..56d3ebed7bac 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -4332,6 +4332,9 @@ int vfs_unlink(struct mnt_idmap *idmap, struct inode *dir,
else {
error = security_inode_unlink(dir, dentry);
if (!error) {
+ error = try_break_deleg(dir, delegated_inode);
+ if (error)
+ goto out;
error = try_break_deleg(target, delegated_inode);
if (error)
goto out;
@@ -4603,9 +4606,12 @@ int vfs_link(struct dentry *old_dentry, struct mnt_idmap *idmap,
else if (max_links && inode->i_nlink >= max_links)
error = -EMLINK;
else {
- error = try_break_deleg(inode, delegated_inode);
- if (!error)
- error = dir->i_op->link(old_dentry, dir, new_dentry);
+ error = try_break_deleg(dir, delegated_inode);
+ if (!error) {
+ error = try_break_deleg(inode, delegated_inode);
+ if (!error)
+ error = dir->i_op->link(old_dentry, dir, new_dentry);
+ }
}

if (!error && (inode->i_state & I_LINKABLE)) {
@@ -4870,6 +4876,14 @@ int vfs_rename(struct renamedata *rd)
old_dir->i_nlink >= max_links)
goto out;
}
+ error = try_break_deleg(old_dir, delegated_inode);
+ if (error)
+ goto out;
+ if (new_dir != old_dir) {
+ error = try_break_deleg(new_dir, delegated_inode);
+ if (error)
+ goto out;
+ }
if (!is_dir) {
error = try_break_deleg(source, delegated_inode);
if (error)

--
2.44.0

2024-03-17 00:00:49

by Al Viro

Subject: Re: [PATCH RFC 03/24] vfs: add try_break_deleg calls for parents to vfs_{link,rename,unlink}

On Fri, Mar 15, 2024 at 12:52:54PM -0400, Jeff Layton wrote:
> @@ -4603,9 +4606,12 @@ int vfs_link(struct dentry *old_dentry, struct mnt_idmap *idmap,
> else if (max_links && inode->i_nlink >= max_links)
> error = -EMLINK;
> else {
> - error = try_break_deleg(inode, delegated_inode);
> - if (!error)
> - error = dir->i_op->link(old_dentry, dir, new_dentry);
> + error = try_break_deleg(dir, delegated_inode);
> + if (!error) {
> + error = try_break_deleg(inode, delegated_inode);
> + if (!error)
> + error = dir->i_op->link(old_dentry, dir, new_dentry);
> + }

A minor nit: that might be easier to follow as
error = try_break_deleg(dir, delegated_inode);
if (!error)
error = try_break_deleg(inode, delegated_inode);
if (!error)
error = dir->i_op->link(old_dentry, dir, new_dentry);

and let the compiler deal with optimizing it - any C compiler is going to be
able to figure out that one out. vfs_link() is a mix of those styles anyway -
we have
if (!error && (inode->i_state & I_LINKABLE)) {
spin_lock(&inode->i_lock);
inode->i_state &= ~I_LINKABLE;
spin_unlock(&inode->i_lock);
}
immediately afterwards; might as well make that consistent, especially since
you are getting more shallow nesting that way.

2024-03-17 14:10:02

by Jeff Layton

Subject: Re: [PATCH RFC 03/24] vfs: add try_break_deleg calls for parents to vfs_{link,rename,unlink}

On Sat, 2024-03-16 at 23:57 +0000, Al Viro wrote:
> On Fri, Mar 15, 2024 at 12:52:54PM -0400, Jeff Layton wrote:
> > @@ -4603,9 +4606,12 @@ int vfs_link(struct dentry *old_dentry, struct mnt_idmap *idmap,
> > else if (max_links && inode->i_nlink >= max_links)
> > error = -EMLINK;
> > else {
> > - error = try_break_deleg(inode, delegated_inode);
> > - if (!error)
> > - error = dir->i_op->link(old_dentry, dir, new_dentry);
> > + error = try_break_deleg(dir, delegated_inode);
> > + if (!error) {
> > + error = try_break_deleg(inode, delegated_inode);
> > + if (!error)
> > + error = dir->i_op->link(old_dentry, dir, new_dentry);
> > + }
>
> A minor nit: that might be easier to follow as
> error = try_break_deleg(dir, delegated_inode);
> if (!error)
> error = try_break_deleg(inode, delegated_inode);
> if (!error)
> error = dir->i_op->link(old_dentry, dir, new_dentry);
>
> and let the compiler deal with optimizing it - any C compiler is going to be
> able to figure out that one out. vfs_link() is a mix of those styles anyway -
> we have
> if (!error && (inode->i_state & I_LINKABLE)) {
> spin_lock(&inode->i_lock);
> inode->i_state &= ~I_LINKABLE;
> spin_unlock(&inode->i_lock);
> }
> immediately afterwards; might as well make that consistent, especially since
> you are getting more shallow nesting that way.

Sounds good. Fixed in my tree.

Thanks for the review so far!
--
Jeff Layton <[email protected]>