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exfat: simplify exfat_lookup()

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1) d_splice_alias() handles ERR_PTR() for inode just fine
2) no need to even look for existing aliases in case of directory inodes;
   just punt to d_splice_alias(), it'll do the right thing
3) no need to bother with 'd_unhashed(alias)' case - d_find_alias()
   would've returned that only in case of a directory, and d_splice_alias()
   will handle that just fine on its own.
4) exfat_d_anon_disconn() is entirely pointless now - we only get to
   evaluating it in case dentry->d_parent == alias->d_parent and
   alias being a non-directory.  But in that case IS_ROOT(alias) can't
   possibly be true - that would've reqiured alias == alias->d_parent,
   i.e alias == dentry->d_parent and dentry->d_parent is guaranteed to
   be a directory.  So exfat_d_anon_disconn() would always return false
   when it's called, which makes && !exfat_d_anon_disconn(alias)
   a no-op.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
This commit is contained in:
Al Viro 2026-04-24 22:29:06 +09:00 committed by Namjae Jeon
parent 3f5f8ee991
commit 623f0aa1ec
1 changed files with 13 additions and 43 deletions
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56
fs/exfat/namei.c
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@ -705,71 +705,44 @@ static int exfat_find(struct inode *dir, const struct qstr *qname,
return 0;
}
static int exfat_d_anon_disconn(struct dentry *dentry)
{
return IS_ROOT(dentry) && (dentry->d_flags & DCACHE_DISCONNECTED);
}
static struct dentry *exfat_lookup(struct inode *dir, struct dentry *dentry,
unsigned int flags)
{
struct super_block *sb = dir->i_sb;
struct inode *inode;
struct inode *inode = NULL;
struct dentry *alias;
struct exfat_dir_entry info;
int err;
loff_t i_pos;
mode_t i_mode;
mutex_lock(&EXFAT_SB(sb)->s_lock);
err = exfat_find(dir, &dentry->d_name, &info);
if (err) {
if (err == -ENOENT) {
inode = NULL;
goto out;
}
goto unlock;
if (unlikely(err != -ENOENT))
inode = ERR_PTR(err);
goto out;
}
i_pos = exfat_make_i_pos(&info);
inode = exfat_build_inode(sb, &info, i_pos);
err = PTR_ERR_OR_ZERO(inode);
if (err)
goto unlock;
if (IS_ERR(inode) || S_ISDIR(inode->i_mode))
goto out;
i_mode = inode->i_mode;
alias = d_find_alias(inode);
/*
* Checking "alias->d_parent == dentry->d_parent" to make sure
* FS is not corrupted (especially double linked dir).
*/
if (alias && alias->d_parent == dentry->d_parent &&
!exfat_d_anon_disconn(alias)) {
if (alias && alias->d_parent == dentry->d_parent) {
/*
* Unhashed alias is able to exist because of revalidate()
* called by lookup_fast. You can easily make this status
* by calling create and lookup concurrently
* In such case, we reuse an alias instead of new dentry
* This inode has a hashed alias dentry with different
* name. This means, the user did ->lookup() by an
* another name (longname vs 8.3 alias of it) in past.
*
* Switch to new one for reason of locality if possible.
*/
if (d_unhashed(alias)) {
WARN_ON(alias->d_name.hash_len !=
dentry->d_name.hash_len);
exfat_info(sb, "rehashed a dentry(%p) in read lookup",
alias);
d_drop(dentry);
d_rehash(alias);
} else if (!S_ISDIR(i_mode)) {
/*
* This inode has non anonymous-DCACHE_DISCONNECTED
* dentry. This means, the user did ->lookup() by an
* another name (longname vs 8.3 alias of it) in past.
*
* Switch to new one for reason of locality if possible.
*/
d_move(alias, dentry);
}
d_move(alias, dentry);
iput(inode);
mutex_unlock(&EXFAT_SB(sb)->s_lock);
return alias;
@ -781,9 +754,6 @@ static struct dentry *exfat_lookup(struct inode *dir, struct dentry *dentry,
exfat_d_version_set(dentry, inode_query_iversion(dir));
return d_splice_alias(inode, dentry);
unlock:
mutex_unlock(&EXFAT_SB(sb)->s_lock);
return ERR_PTR(err);
}
/* remove an entry, BUT don't truncate */