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authorAl Viro <viro@zeniv.linux.org.uk>2022-05-13 00:08:03 +0300
committerAl Viro <viro@zeniv.linux.org.uk>2022-05-15 01:49:01 +0300
commit6319194ec57b0452dcda4589d24c4e7db299c5bf (patch)
treed65162000bc0031c8e5946aa7135c9dad7496d6c /fs/file.c
parent81132a39c152ca09832b9e4cb748129cee5f55ec (diff)
downloadlinux-6319194ec57b0452dcda4589d24c4e7db299c5bf.tar.xz
Unify the primitives for file descriptor closing
Currently we have 3 primitives for removing an opened file from descriptor table - pick_file(), __close_fd_get_file() and close_fd_get_file(). Their calling conventions are rather odd and there's a code duplication for no good reason. They can be unified - 1) have __range_close() cap max_fd in the very beginning; that way we don't need separate way for pick_file() to report being past the end of descriptor table. 2) make {__,}close_fd_get_file() return file (or NULL) directly, rather than returning it via struct file ** argument. Don't bother with (bogus) return value - nobody wants that -ENOENT. 3) make pick_file() return NULL on unopened descriptor - the only caller that used to care about the distinction between descriptor past the end of descriptor table and finding NULL in descriptor table doesn't give a damn after (1). 4) lift ->files_lock out of pick_file() That actually simplifies the callers, as well as the primitives themselves. Code duplication is also gone... Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/file.c')
-rw-r--r--fs/file.c77
1 files changed, 29 insertions, 48 deletions
diff --git a/fs/file.c b/fs/file.c
index 4c59f410a48d..dd6692048f4f 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -630,32 +630,23 @@ EXPORT_SYMBOL(fd_install);
* @files: file struct to retrieve file from
* @fd: file descriptor to retrieve file for
*
- * If this functions returns an EINVAL error pointer the fd was beyond the
- * current maximum number of file descriptors for that fdtable.
+ * Context: files_lock must be held.
*
- * Returns: The file associated with @fd, on error returns an error pointer.
+ * Returns: The file associated with @fd (NULL if @fd is not open)
*/
static struct file *pick_file(struct files_struct *files, unsigned fd)
{
+ struct fdtable *fdt = files_fdtable(files);
struct file *file;
- struct fdtable *fdt;
- spin_lock(&files->file_lock);
- fdt = files_fdtable(files);
- if (fd >= fdt->max_fds) {
- file = ERR_PTR(-EINVAL);
- goto out_unlock;
- }
+ if (fd >= fdt->max_fds)
+ return NULL;
+
file = fdt->fd[fd];
- if (!file) {
- file = ERR_PTR(-EBADF);
- goto out_unlock;
+ if (file) {
+ rcu_assign_pointer(fdt->fd[fd], NULL);
+ __put_unused_fd(files, fd);
}
- rcu_assign_pointer(fdt->fd[fd], NULL);
- __put_unused_fd(files, fd);
-
-out_unlock:
- spin_unlock(&files->file_lock);
return file;
}
@@ -664,8 +655,10 @@ int close_fd(unsigned fd)
struct files_struct *files = current->files;
struct file *file;
+ spin_lock(&files->file_lock);
file = pick_file(files, fd);
- if (IS_ERR(file))
+ spin_unlock(&files->file_lock);
+ if (!file)
return -EBADF;
return filp_close(file, files);
@@ -702,20 +695,25 @@ static inline void __range_cloexec(struct files_struct *cur_fds,
static inline void __range_close(struct files_struct *cur_fds, unsigned int fd,
unsigned int max_fd)
{
+ unsigned n;
+
+ rcu_read_lock();
+ n = last_fd(files_fdtable(cur_fds));
+ rcu_read_unlock();
+ max_fd = min(max_fd, n);
+
while (fd <= max_fd) {
struct file *file;
+ spin_lock(&cur_fds->file_lock);
file = pick_file(cur_fds, fd++);
- if (!IS_ERR(file)) {
+ spin_unlock(&cur_fds->file_lock);
+
+ if (file) {
/* found a valid file to close */
filp_close(file, cur_fds);
cond_resched();
- continue;
}
-
- /* beyond the last fd in that table */
- if (PTR_ERR(file) == -EINVAL)
- return;
}
}
@@ -795,26 +793,9 @@ int __close_range(unsigned fd, unsigned max_fd, unsigned int flags)
* See close_fd_get_file() below, this variant assumes current->files->file_lock
* is held.
*/
-int __close_fd_get_file(unsigned int fd, struct file **res)
+struct file *__close_fd_get_file(unsigned int fd)
{
- struct files_struct *files = current->files;
- struct file *file;
- struct fdtable *fdt;
-
- fdt = files_fdtable(files);
- if (fd >= fdt->max_fds)
- goto out_err;
- file = fdt->fd[fd];
- if (!file)
- goto out_err;
- rcu_assign_pointer(fdt->fd[fd], NULL);
- __put_unused_fd(files, fd);
- get_file(file);
- *res = file;
- return 0;
-out_err:
- *res = NULL;
- return -ENOENT;
+ return pick_file(current->files, fd);
}
/*
@@ -822,16 +803,16 @@ out_err:
* The caller must ensure that filp_close() called on the file, and then
* an fput().
*/
-int close_fd_get_file(unsigned int fd, struct file **res)
+struct file *close_fd_get_file(unsigned int fd)
{
struct files_struct *files = current->files;
- int ret;
+ struct file *file;
spin_lock(&files->file_lock);
- ret = __close_fd_get_file(fd, res);
+ file = pick_file(files, fd);
spin_unlock(&files->file_lock);
- return ret;
+ return file;
}
void do_close_on_exec(struct files_struct *files)