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VFS: tidy up do_unlinkat() 

The simplification of locking in the previous patch opens up some room
for tidying up do_unlinkat()

- change all "exit" labels to describe what will happen at the label.
- always goto an exit label on an error - unwrap the "if (!IS_ERR())" branch.
- Move the "slashes" handing inline, but mark it as unlikely()
- simplify use of the "inode" variable - we no longer need to test for NULL.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: NeilBrown <neil@brown.name>
Link: https://patch.msgid.link/20251113002050.676694-4-neilb@ownmail.net
Tested-by: syzbot@syzkaller.appspotmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
NeilBrown 2025-11-13 11:18:26 +11:00 committed by Christian Brauner
parent 4037d966f0
commit 3661a78874
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GPG Key ID: 91C61BC06578DCA2
1 changed files with 26 additions and 29 deletions
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55
fs/namei.c
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@ -4755,65 +4755,62 @@ int do_unlinkat(int dfd, struct filename *name)
struct path path;
struct qstr last;
int type;
struct inode *inode = NULL;
struct inode *inode;
struct inode *delegated_inode = NULL;
unsigned int lookup_flags = 0;
retry:
error = filename_parentat(dfd, name, lookup_flags, &path, &last, &type);
if (error)
goto exit1;
goto exit_putname;
error = -EISDIR;
if (type != LAST_NORM)
goto exit2;
goto exit_path_put;
error = mnt_want_write(path.mnt);
if (error)
goto exit2;
goto exit_path_put;
retry_deleg:
dentry = start_dirop(path.dentry, &last, lookup_flags);
error = PTR_ERR(dentry);
if (!IS_ERR(dentry)) {
if (IS_ERR(dentry))
goto exit_drop_write;
/* Why not before? Because we want correct error value */
if (last.name[last.len])
goto slashes;
inode = dentry->d_inode;
ihold(inode);
error = security_path_unlink(&path, dentry);
if (error)
goto exit3;
error = vfs_unlink(mnt_idmap(path.mnt), path.dentry->d_inode,
dentry, &delegated_inode);
exit3:
/* Why not before? Because we want correct error value */
if (unlikely(last.name[last.len])) {
if (d_is_dir(dentry))
error = -EISDIR;
else
error = -ENOTDIR;
end_dirop(dentry);
goto exit_drop_write;
}
if (inode)
iput(inode); /* truncate the inode here */
inode = NULL;
inode = dentry->d_inode;
ihold(inode);
error = security_path_unlink(&path, dentry);
if (error)
goto exit_end_dirop;
error = vfs_unlink(mnt_idmap(path.mnt), path.dentry->d_inode,
dentry, &delegated_inode);
exit_end_dirop:
end_dirop(dentry);
iput(inode); /* truncate the inode here */
if (delegated_inode) {
error = break_deleg_wait(&delegated_inode);
if (!error)
goto retry_deleg;
}
exit_drop_write:
mnt_drop_write(path.mnt);
exit2:
exit_path_put:
path_put(&path);
if (retry_estale(error, lookup_flags)) {
lookup_flags |= LOOKUP_REVAL;
inode = NULL;
goto retry;
}
exit1:
exit_putname:
putname(name);
return error;
slashes:
if (d_is_dir(dentry))
error = -EISDIR;
else
error = -ENOTDIR;
goto exit3;
}
SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag)