From 52732bb9abc9ee5b82ed62edef51be4a255fc78a Mon Sep 17 00:00:00 2001 From: Yu Ma Date: Wed, 17 Jul 2024 10:50:16 -0400 Subject: fs/file.c: remove sanity_check and add likely/unlikely in alloc_fd() alloc_fd() has a sanity check inside to make sure the struct file mapping to the allocated fd is NULL. Remove this sanity check since it can be assured by exisitng zero initilization and NULL set when recycling fd. Meanwhile, add likely/unlikely and expand_file() call avoidance to reduce the work under file_lock. Reviewed-by: Jan Kara Reviewed-by: Tim Chen Signed-off-by: Yu Ma Link: https://lore.kernel.org/r/20240717145018.3972922-2-yu.ma@intel.com Signed-off-by: Christian Brauner Signed-off-by: Al Viro --- fs/file.c | 33 ++++++++++++++------------------- 1 file changed, 14 insertions(+), 19 deletions(-) (limited to 'fs/file.c') diff --git a/fs/file.c b/fs/file.c index 8e8f504782bf..90b8aa2378cc 100644 --- a/fs/file.c +++ b/fs/file.c @@ -496,7 +496,7 @@ repeat: if (fd < files->next_fd) fd = files->next_fd; - if (fd < fdt->max_fds) + if (likely(fd < fdt->max_fds)) fd = find_next_fd(fdt, fd); /* @@ -504,19 +504,21 @@ repeat: * will limit the total number of files that can be opened. */ error = -EMFILE; - if (fd >= end) + if (unlikely(fd >= end)) goto out; - error = expand_files(files, fd); - if (error < 0) - goto out; + if (unlikely(fd >= fdt->max_fds)) { + error = expand_files(files, fd); + if (error < 0) + goto out; - /* - * If we needed to expand the fs array we - * might have blocked - try again. - */ - if (error) - goto repeat; + /* + * If we needed to expand the fs array we + * might have blocked - try again. + */ + if (error) + goto repeat; + } if (start <= files->next_fd) files->next_fd = fd + 1; @@ -527,13 +529,6 @@ repeat: else __clear_close_on_exec(fd, fdt); error = fd; -#if 1 - /* Sanity check */ - if (rcu_access_pointer(fdt->fd[fd]) != NULL) { - printk(KERN_WARNING "alloc_fd: slot %d not NULL!\n", fd); - rcu_assign_pointer(fdt->fd[fd], NULL); - } -#endif out: spin_unlock(&files->file_lock); @@ -599,7 +594,7 @@ void fd_install(unsigned int fd, struct file *file) rcu_read_unlock_sched(); spin_lock(&files->file_lock); fdt = files_fdtable(files); - BUG_ON(fdt->fd[fd] != NULL); + WARN_ON(fdt->fd[fd] != NULL); rcu_assign_pointer(fdt->fd[fd], file); spin_unlock(&files->file_lock); return; -- cgit