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fs: factor out backing_file_splice_{read,write}() helpers

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There is not much in those helpers, but it makes sense to have them
logically next to the backing_file_{read,write}_iter() helpers as they
may grow more common logic in the future.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
This commit is contained in:
Amir Goldstein 2023-10-13 12:13:12 +03:00
parent a6293b3e28
commit 9b7e9e2f5d
3 changed files with 72 additions and 20 deletions
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51
fs/backing-file.c
View File

@ -10,6 +10,7 @@
#include <linux/fs.h>
#include <linux/backing-file.h>
#include <linux/splice.h>
#include "internal.h"
@ -245,6 +246,56 @@ out:
}
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);
static int __init backing_aio_init(void)
{
backing_aio_cachep = kmem_cache_create("backing_aio",

33
fs/overlayfs/file.c
View File

@ -9,7 +9,6 @@
#include <linux/xattr.h>
#include <linux/uio.h>
#include <linux/uaccess.h>
#include <linux/splice.h>
#include <linux/security.h>
#include <linux/mm.h>
#include <linux/fs.h>
@ -332,20 +331,21 @@ static ssize_t ovl_splice_read(struct file *in, loff_t *ppos,
struct pipe_inode_info *pipe, size_t len,
unsigned int flags)
{
const struct cred *old_cred;
struct fd real;
ssize_t ret;
struct backing_file_ctx ctx = {
.cred = ovl_creds(file_inode(in)->i_sb),
.user_file = in,
.accessed = ovl_file_accessed,
};
ret = ovl_real_fdget(in, &real);
if (ret)
return ret;
old_cred = ovl_override_creds(file_inode(in)->i_sb);
ret = vfs_splice_read(real.file, ppos, pipe, len, flags);
revert_creds(old_cred);
ovl_file_accessed(in);
ret = backing_file_splice_read(real.file, ppos, pipe, len, flags, &ctx);
fdput(real);
return ret;
}
@ -361,30 +361,23 @@ static ssize_t ovl_splice_write(struct pipe_inode_info *pipe, struct file *out,
loff_t *ppos, size_t len, unsigned int flags)
{
struct fd real;
const struct cred *old_cred;
struct inode *inode = file_inode(out);
ssize_t ret;
struct backing_file_ctx ctx = {
.cred = ovl_creds(inode->i_sb),
.user_file = out,
.end_write = ovl_file_modified,
};
inode_lock(inode);
/* Update mode */
ovl_copyattr(inode);
ret = file_remove_privs(out);
if (ret)
goto out_unlock;
ret = ovl_real_fdget(out, &real);
if (ret)
goto out_unlock;
old_cred = ovl_override_creds(inode->i_sb);
file_start_write(real.file);
ret = iter_file_splice_write(pipe, real.file, ppos, len, flags);
file_end_write(real.file);
/* Update size */
ovl_file_modified(out);
revert_creds(old_cred);
ret = backing_file_splice_write(pipe, real.file, ppos, len, flags, &ctx);
fdput(real);
out_unlock:

8
include/linux/backing-file.h
View File

@ -28,5 +28,13 @@ ssize_t backing_file_read_iter(struct file *file, struct iov_iter *iter,
ssize_t backing_file_write_iter(struct file *file, struct iov_iter *iter,
struct kiocb *iocb, int flags,
struct backing_file_ctx *ctx);
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);
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);
#endif /* _LINUX_BACKING_FILE_H */