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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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a88c955fcf
That really shouldn't have "get" in there as that implies we're bumping the reference count which we don't do at all. We used to but not anmore. Now we're just closing the fd and pick that file from the fdtable without bumping the reference count. Update the wrong documentation while at it. Link: https://lore.kernel.org/r/20231130-vfs-files-fixes-v1-1-e73ca6f4ea83@kernel.org Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Christian Brauner <brauner@kernel.org>
128 lines
3.5 KiB
C
128 lines
3.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* descriptor table internals; you almost certainly want file.h instead.
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*/
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#ifndef __LINUX_FDTABLE_H
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#define __LINUX_FDTABLE_H
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#include <linux/posix_types.h>
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#include <linux/compiler.h>
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#include <linux/spinlock.h>
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#include <linux/rcupdate.h>
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#include <linux/nospec.h>
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#include <linux/types.h>
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#include <linux/init.h>
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#include <linux/fs.h>
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#include <linux/atomic.h>
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/*
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* The default fd array needs to be at least BITS_PER_LONG,
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* as this is the granularity returned by copy_fdset().
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*/
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#define NR_OPEN_DEFAULT BITS_PER_LONG
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#define NR_OPEN_MAX ~0U
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struct fdtable {
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unsigned int max_fds;
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struct file __rcu **fd; /* current fd array */
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unsigned long *close_on_exec;
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unsigned long *open_fds;
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unsigned long *full_fds_bits;
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struct rcu_head rcu;
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};
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static inline bool close_on_exec(unsigned int fd, const struct fdtable *fdt)
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{
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return test_bit(fd, fdt->close_on_exec);
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}
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static inline bool fd_is_open(unsigned int fd, const struct fdtable *fdt)
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{
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return test_bit(fd, fdt->open_fds);
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}
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/*
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* Open file table structure
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*/
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struct files_struct {
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/*
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* read mostly part
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*/
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atomic_t count;
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bool resize_in_progress;
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wait_queue_head_t resize_wait;
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struct fdtable __rcu *fdt;
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struct fdtable fdtab;
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/*
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* written part on a separate cache line in SMP
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*/
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spinlock_t file_lock ____cacheline_aligned_in_smp;
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unsigned int next_fd;
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unsigned long close_on_exec_init[1];
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unsigned long open_fds_init[1];
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unsigned long full_fds_bits_init[1];
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struct file __rcu * fd_array[NR_OPEN_DEFAULT];
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};
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struct file_operations;
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struct vfsmount;
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struct dentry;
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#define rcu_dereference_check_fdtable(files, fdtfd) \
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rcu_dereference_check((fdtfd), lockdep_is_held(&(files)->file_lock))
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#define files_fdtable(files) \
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rcu_dereference_check_fdtable((files), (files)->fdt)
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/*
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* The caller must ensure that fd table isn't shared or hold rcu or file lock
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*/
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static inline struct file *files_lookup_fd_raw(struct files_struct *files, unsigned int fd)
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{
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struct fdtable *fdt = rcu_dereference_raw(files->fdt);
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unsigned long mask = array_index_mask_nospec(fd, fdt->max_fds);
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struct file *needs_masking;
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/*
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* 'mask' is zero for an out-of-bounds fd, all ones for ok.
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* 'fd&mask' is 'fd' for ok, or 0 for out of bounds.
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*
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* Accessing fdt->fd[0] is ok, but needs masking of the result.
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*/
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needs_masking = rcu_dereference_raw(fdt->fd[fd&mask]);
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return (struct file *)(mask & (unsigned long)needs_masking);
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}
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static inline struct file *files_lookup_fd_locked(struct files_struct *files, unsigned int fd)
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{
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RCU_LOCKDEP_WARN(!lockdep_is_held(&files->file_lock),
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"suspicious rcu_dereference_check() usage");
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return files_lookup_fd_raw(files, fd);
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}
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struct file *lookup_fdget_rcu(unsigned int fd);
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struct file *task_lookup_fdget_rcu(struct task_struct *task, unsigned int fd);
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struct file *task_lookup_next_fdget_rcu(struct task_struct *task, unsigned int *fd);
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struct task_struct;
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void put_files_struct(struct files_struct *fs);
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int unshare_files(void);
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struct files_struct *dup_fd(struct files_struct *, unsigned, int *) __latent_entropy;
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void do_close_on_exec(struct files_struct *);
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int iterate_fd(struct files_struct *, unsigned,
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int (*)(const void *, struct file *, unsigned),
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const void *);
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extern int close_fd(unsigned int fd);
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extern int __close_range(unsigned int fd, unsigned int max_fd, unsigned int flags);
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extern struct file *file_close_fd(unsigned int fd);
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extern int unshare_fd(unsigned long unshare_flags, unsigned int max_fds,
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struct files_struct **new_fdp);
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extern struct kmem_cache *files_cachep;
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#endif /* __LINUX_FDTABLE_H */
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