358 lines
8.3 KiB
C
358 lines
8.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
/*
|
|
* Common helpers for stackable filesystems and backing files.
|
|
*
|
|
* Forked from fs/overlayfs/file.c.
|
|
*
|
|
* Copyright (C) 2017 Red Hat, Inc.
|
|
* Copyright (C) 2023 CTERA Networks.
|
|
*/
|
|
|
|
#include <linux/fs.h>
|
|
#include <linux/backing-file.h>
|
|
#include <linux/splice.h>
|
|
#include <linux/mm.h>
|
|
|
|
#include "internal.h"
|
|
|
|
/**
|
|
* backing_file_open - open a backing file for kernel internal use
|
|
* @user_path: path that the user reuqested to open
|
|
* @flags: open flags
|
|
* @real_path: path of the backing file
|
|
* @cred: credentials for open
|
|
*
|
|
* Open a backing file for a stackable filesystem (e.g., overlayfs).
|
|
* @user_path may be on the stackable filesystem and @real_path on the
|
|
* underlying filesystem. In this case, we want to be able to return the
|
|
* @user_path of the stackable filesystem. This is done by embedding the
|
|
* returned file into a container structure that also stores the stacked
|
|
* file's path, which can be retrieved using backing_file_user_path().
|
|
*/
|
|
struct file *backing_file_open(const struct path *user_path, int flags,
|
|
const struct path *real_path,
|
|
const struct cred *cred)
|
|
{
|
|
struct file *f;
|
|
int error;
|
|
|
|
f = alloc_empty_backing_file(flags, cred);
|
|
if (IS_ERR(f))
|
|
return f;
|
|
|
|
path_get(user_path);
|
|
*backing_file_user_path(f) = *user_path;
|
|
error = vfs_open(real_path, f);
|
|
if (error) {
|
|
fput(f);
|
|
f = ERR_PTR(error);
|
|
}
|
|
|
|
return f;
|
|
}
|
|
EXPORT_SYMBOL_GPL(backing_file_open);
|
|
|
|
struct file *backing_tmpfile_open(const struct path *user_path, int flags,
|
|
const struct path *real_parentpath,
|
|
umode_t mode, const struct cred *cred)
|
|
{
|
|
struct mnt_idmap *real_idmap = mnt_idmap(real_parentpath->mnt);
|
|
struct file *f;
|
|
int error;
|
|
|
|
f = alloc_empty_backing_file(flags, cred);
|
|
if (IS_ERR(f))
|
|
return f;
|
|
|
|
path_get(user_path);
|
|
*backing_file_user_path(f) = *user_path;
|
|
error = vfs_tmpfile(real_idmap, real_parentpath, f, mode);
|
|
if (error) {
|
|
fput(f);
|
|
f = ERR_PTR(error);
|
|
}
|
|
return f;
|
|
}
|
|
EXPORT_SYMBOL(backing_tmpfile_open);
|
|
|
|
struct backing_aio {
|
|
struct kiocb iocb;
|
|
refcount_t ref;
|
|
struct kiocb *orig_iocb;
|
|
/* used for aio completion */
|
|
void (*end_write)(struct file *);
|
|
struct work_struct work;
|
|
long res;
|
|
};
|
|
|
|
static struct kmem_cache *backing_aio_cachep;
|
|
|
|
#define BACKING_IOCB_MASK \
|
|
(IOCB_NOWAIT | IOCB_HIPRI | IOCB_DSYNC | IOCB_SYNC | IOCB_APPEND)
|
|
|
|
static rwf_t iocb_to_rw_flags(int flags)
|
|
{
|
|
return (__force rwf_t)(flags & BACKING_IOCB_MASK);
|
|
}
|
|
|
|
static void backing_aio_put(struct backing_aio *aio)
|
|
{
|
|
if (refcount_dec_and_test(&aio->ref)) {
|
|
fput(aio->iocb.ki_filp);
|
|
kmem_cache_free(backing_aio_cachep, aio);
|
|
}
|
|
}
|
|
|
|
static void backing_aio_cleanup(struct backing_aio *aio, long res)
|
|
{
|
|
struct kiocb *iocb = &aio->iocb;
|
|
struct kiocb *orig_iocb = aio->orig_iocb;
|
|
|
|
if (aio->end_write)
|
|
aio->end_write(orig_iocb->ki_filp);
|
|
|
|
orig_iocb->ki_pos = iocb->ki_pos;
|
|
backing_aio_put(aio);
|
|
}
|
|
|
|
static void backing_aio_rw_complete(struct kiocb *iocb, long res)
|
|
{
|
|
struct backing_aio *aio = container_of(iocb, struct backing_aio, iocb);
|
|
struct kiocb *orig_iocb = aio->orig_iocb;
|
|
|
|
if (iocb->ki_flags & IOCB_WRITE)
|
|
kiocb_end_write(iocb);
|
|
|
|
backing_aio_cleanup(aio, res);
|
|
orig_iocb->ki_complete(orig_iocb, res);
|
|
}
|
|
|
|
static void backing_aio_complete_work(struct work_struct *work)
|
|
{
|
|
struct backing_aio *aio = container_of(work, struct backing_aio, work);
|
|
|
|
backing_aio_rw_complete(&aio->iocb, aio->res);
|
|
}
|
|
|
|
static void backing_aio_queue_completion(struct kiocb *iocb, long res)
|
|
{
|
|
struct backing_aio *aio = container_of(iocb, struct backing_aio, iocb);
|
|
|
|
/*
|
|
* Punt to a work queue to serialize updates of mtime/size.
|
|
*/
|
|
aio->res = res;
|
|
INIT_WORK(&aio->work, backing_aio_complete_work);
|
|
queue_work(file_inode(aio->orig_iocb->ki_filp)->i_sb->s_dio_done_wq,
|
|
&aio->work);
|
|
}
|
|
|
|
static int backing_aio_init_wq(struct kiocb *iocb)
|
|
{
|
|
struct super_block *sb = file_inode(iocb->ki_filp)->i_sb;
|
|
|
|
if (sb->s_dio_done_wq)
|
|
return 0;
|
|
|
|
return sb_init_dio_done_wq(sb);
|
|
}
|
|
|
|
|
|
ssize_t backing_file_read_iter(struct file *file, struct iov_iter *iter,
|
|
struct kiocb *iocb, int flags,
|
|
struct backing_file_ctx *ctx)
|
|
{
|
|
struct backing_aio *aio = NULL;
|
|
const struct cred *old_cred;
|
|
ssize_t ret;
|
|
|
|
if (WARN_ON_ONCE(!(file->f_mode & FMODE_BACKING)))
|
|
return -EIO;
|
|
|
|
if (!iov_iter_count(iter))
|
|
return 0;
|
|
|
|
if (iocb->ki_flags & IOCB_DIRECT &&
|
|
!(file->f_mode & FMODE_CAN_ODIRECT))
|
|
return -EINVAL;
|
|
|
|
old_cred = override_creds(ctx->cred);
|
|
if (is_sync_kiocb(iocb)) {
|
|
rwf_t rwf = iocb_to_rw_flags(flags);
|
|
|
|
ret = vfs_iter_read(file, iter, &iocb->ki_pos, rwf);
|
|
} else {
|
|
ret = -ENOMEM;
|
|
aio = kmem_cache_zalloc(backing_aio_cachep, GFP_KERNEL);
|
|
if (!aio)
|
|
goto out;
|
|
|
|
aio->orig_iocb = iocb;
|
|
kiocb_clone(&aio->iocb, iocb, get_file(file));
|
|
aio->iocb.ki_complete = backing_aio_rw_complete;
|
|
refcount_set(&aio->ref, 2);
|
|
ret = vfs_iocb_iter_read(file, &aio->iocb, iter);
|
|
backing_aio_put(aio);
|
|
if (ret != -EIOCBQUEUED)
|
|
backing_aio_cleanup(aio, ret);
|
|
}
|
|
out:
|
|
revert_creds(old_cred);
|
|
|
|
if (ctx->accessed)
|
|
ctx->accessed(ctx->user_file);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(backing_file_read_iter);
|
|
|
|
ssize_t backing_file_write_iter(struct file *file, struct iov_iter *iter,
|
|
struct kiocb *iocb, int flags,
|
|
struct backing_file_ctx *ctx)
|
|
{
|
|
const struct cred *old_cred;
|
|
ssize_t ret;
|
|
|
|
if (WARN_ON_ONCE(!(file->f_mode & FMODE_BACKING)))
|
|
return -EIO;
|
|
|
|
if (!iov_iter_count(iter))
|
|
return 0;
|
|
|
|
ret = file_remove_privs(ctx->user_file);
|
|
if (ret)
|
|
return ret;
|
|
|
|
if (iocb->ki_flags & IOCB_DIRECT &&
|
|
!(file->f_mode & FMODE_CAN_ODIRECT))
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* Stacked filesystems don't support deferred completions, don't copy
|
|
* this property in case it is set by the issuer.
|
|
*/
|
|
flags &= ~IOCB_DIO_CALLER_COMP;
|
|
|
|
old_cred = override_creds(ctx->cred);
|
|
if (is_sync_kiocb(iocb)) {
|
|
rwf_t rwf = iocb_to_rw_flags(flags);
|
|
|
|
ret = vfs_iter_write(file, iter, &iocb->ki_pos, rwf);
|
|
if (ctx->end_write)
|
|
ctx->end_write(ctx->user_file);
|
|
} else {
|
|
struct backing_aio *aio;
|
|
|
|
ret = backing_aio_init_wq(iocb);
|
|
if (ret)
|
|
goto out;
|
|
|
|
ret = -ENOMEM;
|
|
aio = kmem_cache_zalloc(backing_aio_cachep, GFP_KERNEL);
|
|
if (!aio)
|
|
goto out;
|
|
|
|
aio->orig_iocb = iocb;
|
|
aio->end_write = ctx->end_write;
|
|
kiocb_clone(&aio->iocb, iocb, get_file(file));
|
|
aio->iocb.ki_flags = flags;
|
|
aio->iocb.ki_complete = backing_aio_queue_completion;
|
|
refcount_set(&aio->ref, 2);
|
|
ret = vfs_iocb_iter_write(file, &aio->iocb, iter);
|
|
backing_aio_put(aio);
|
|
if (ret != -EIOCBQUEUED)
|
|
backing_aio_cleanup(aio, ret);
|
|
}
|
|
out:
|
|
revert_creds(old_cred);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(backing_file_write_iter);
|
|
|
|
ssize_t backing_file_splice_read(struct file *in, loff_t *ppos,
|
|
struct pipe_inode_info *pipe, size_t len,
|
|
unsigned int flags,
|
|
struct backing_file_ctx *ctx)
|
|
{
|
|
const struct cred *old_cred;
|
|
ssize_t ret;
|
|
|
|
if (WARN_ON_ONCE(!(in->f_mode & FMODE_BACKING)))
|
|
return -EIO;
|
|
|
|
old_cred = override_creds(ctx->cred);
|
|
ret = vfs_splice_read(in, ppos, pipe, len, flags);
|
|
revert_creds(old_cred);
|
|
|
|
if (ctx->accessed)
|
|
ctx->accessed(ctx->user_file);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(backing_file_splice_read);
|
|
|
|
ssize_t backing_file_splice_write(struct pipe_inode_info *pipe,
|
|
struct file *out, loff_t *ppos, size_t len,
|
|
unsigned int flags,
|
|
struct backing_file_ctx *ctx)
|
|
{
|
|
const struct cred *old_cred;
|
|
ssize_t ret;
|
|
|
|
if (WARN_ON_ONCE(!(out->f_mode & FMODE_BACKING)))
|
|
return -EIO;
|
|
|
|
ret = file_remove_privs(ctx->user_file);
|
|
if (ret)
|
|
return ret;
|
|
|
|
old_cred = override_creds(ctx->cred);
|
|
file_start_write(out);
|
|
ret = iter_file_splice_write(pipe, out, ppos, len, flags);
|
|
file_end_write(out);
|
|
revert_creds(old_cred);
|
|
|
|
if (ctx->end_write)
|
|
ctx->end_write(ctx->user_file);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(backing_file_splice_write);
|
|
|
|
int backing_file_mmap(struct file *file, struct vm_area_struct *vma,
|
|
struct backing_file_ctx *ctx)
|
|
{
|
|
const struct cred *old_cred;
|
|
int ret;
|
|
|
|
if (WARN_ON_ONCE(!(file->f_mode & FMODE_BACKING)) ||
|
|
WARN_ON_ONCE(ctx->user_file != vma->vm_file))
|
|
return -EIO;
|
|
|
|
if (!file->f_op->mmap)
|
|
return -ENODEV;
|
|
|
|
vma_set_file(vma, file);
|
|
|
|
old_cred = override_creds(ctx->cred);
|
|
ret = call_mmap(vma->vm_file, vma);
|
|
revert_creds(old_cred);
|
|
|
|
if (ctx->accessed)
|
|
ctx->accessed(ctx->user_file);
|
|
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(backing_file_mmap);
|
|
|
|
static int __init backing_aio_init(void)
|
|
{
|
|
backing_aio_cachep = KMEM_CACHE(backing_aio, SLAB_HWCACHE_ALIGN);
|
|
if (!backing_aio_cachep)
|
|
return -ENOMEM;
|
|
|
|
return 0;
|
|
}
|
|
fs_initcall(backing_aio_init);
|