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rpc_pipe: don't overdo directory locking

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Don't try to hold directories locked more than VFS requires;
lock just before getting a child to be made positive (using
simple_start_creating()) and unlock as soon as the child is
created.  There's no benefit in keeping the parent locked
while populating the child - it won't stop dcache lookups anyway.

Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2025-03-22 19:39:40 -04:00
parent 19a6314a99
commit 41a6b9e52b
1 changed files with 9 additions and 35 deletions
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44
net/sunrpc/rpc_pipe.c
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@ -594,22 +594,6 @@ static int __rpc_mkpipe_dentry(struct inode *dir, struct dentry *dentry,
return 0;
}
static struct dentry *__rpc_lookup_create_exclusive(struct dentry *parent,
const char *name)
{
struct qstr q = QSTR(name);
struct dentry *dentry = try_lookup_noperm(&q, parent);
if (!dentry) {
dentry = d_alloc(parent, &q);
if (!dentry)
return ERR_PTR(-ENOMEM);
}
if (d_really_is_negative(dentry))
return dentry;
dput(dentry);
return ERR_PTR(-EEXIST);
}
static int rpc_populate(struct dentry *parent,
const struct rpc_filelist *files,
int start, int eof,
@ -619,9 +603,8 @@ static int rpc_populate(struct dentry *parent,
struct dentry *dentry;
int i, err;
inode_lock(dir);
for (i = start; i < eof; i++) {
dentry = __rpc_lookup_create_exclusive(parent, files[i].name);
dentry = simple_start_creating(parent, files[i].name);
err = PTR_ERR(dentry);
if (IS_ERR(dentry))
goto out_bad;
@ -633,20 +616,20 @@ static int rpc_populate(struct dentry *parent,
files[i].mode,
files[i].i_fop,
private);
inode_unlock(dir);
break;
case S_IFDIR:
err = __rpc_mkdir(dir, dentry,
files[i].mode,
NULL,
private);
inode_unlock(dir);
}
if (err != 0)
goto out_bad;
}
inode_unlock(dir);
return 0;
out_bad:
inode_unlock(dir);
printk(KERN_WARNING "%s: %s failed to populate directory %pd\n",
__FILE__, __func__, parent);
return err;
@ -660,27 +643,21 @@ static struct dentry *rpc_mkdir_populate(struct dentry *parent,
struct inode *dir = d_inode(parent);
int error;
inode_lock_nested(dir, I_MUTEX_PARENT);
dentry = __rpc_lookup_create_exclusive(parent, name);
dentry = simple_start_creating(parent, name);
if (IS_ERR(dentry))
goto out;
return dentry;
error = __rpc_mkdir(dir, dentry, mode, NULL, private);
inode_unlock(dir);
if (error != 0)
goto out_err;
return ERR_PTR(error);
if (populate != NULL) {
error = populate(dentry, args_populate);
if (error) {
inode_unlock(dir);
simple_recursive_removal(dentry, NULL);
return ERR_PTR(error);
}
}
out:
inode_unlock(dir);
return dentry;
out_err:
dentry = ERR_PTR(error);
goto out;
}
/**
@ -715,12 +692,9 @@ int rpc_mkpipe_dentry(struct dentry *parent, const char *name,
if (pipe->ops->downcall == NULL)
umode &= ~0222;
inode_lock_nested(dir, I_MUTEX_PARENT);
dentry = __rpc_lookup_create_exclusive(parent, name);
if (IS_ERR(dentry)) {
inode_unlock(dir);
dentry = simple_start_creating(parent, name);
if (IS_ERR(dentry))
return PTR_ERR(dentry);
}
err = __rpc_mkpipe_dentry(dir, dentry, umode, &rpc_pipe_fops,
private, pipe);
if (unlikely(err))