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overlayfs fixes for 4.19-rc4 

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Merge tag 'ovl-fixes-4.19-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs

Pull overlayfs fixes from Miklos Szeredi:
 "This fixes a regression in the recent file stacking update, reported
  and fixed by Amir Goldstein. The fix is fairly trivial, but involves
  adding a fadvise() f_op and the associated churn in the vfs. As
  discussed on -fsdevel, there are other possible uses for this method,
  than allowing proper stacking for overlays.

  And there's one other fix for a syzkaller detected oops"

* tag 'ovl-fixes-4.19-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
  ovl: fix oopses in ovl_fill_super() failure paths
  ovl: add ovl_fadvise()
  vfs: implement readahead(2) using POSIX_FADV_WILLNEED
  vfs: add the fadvise() file operation
  Documentation/filesystems: update documentation of file_operations
  ovl: fix GPF in swapfile_activate of file from overlayfs over xfs
  ovl: respect FIEMAP_FLAG_SYNC flag
This commit is contained in:
Linus Torvalds 2018-09-13 19:21:40 -10:00
parent 4d8d9f540b 8c25741aaa
commit 48751b562b
8 changed files with 134 additions and 80 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
Documentation/filesystems/vfs.txt
View File

@ -848,7 +848,7 @@ struct file_operations
----------------------
This describes how the VFS can manipulate an open file. As of kernel
4.1, the following members are defined:
4.18, the following members are defined:
struct file_operations {
struct module *owner;
@ -858,11 +858,11 @@ struct file_operations {
ssize_t (*read_iter) (struct kiocb *, struct iov_iter *);
ssize_t (*write_iter) (struct kiocb *, struct iov_iter *);
int (*iterate) (struct file *, struct dir_context *);
int (*iterate_shared) (struct file *, struct dir_context *);
__poll_t (*poll) (struct file *, struct poll_table_struct *);
long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);
long (*compat_ioctl) (struct file *, unsigned int, unsigned long);
int (*mmap) (struct file *, struct vm_area_struct *);
int (*mremap)(struct file *, struct vm_area_struct *);
int (*open) (struct inode *, struct file *);
int (*flush) (struct file *, fl_owner_t id);
int (*release) (struct inode *, struct file *);
@ -882,6 +882,10 @@ struct file_operations {
#ifndef CONFIG_MMU
unsigned (*mmap_capabilities)(struct file *);
#endif
ssize_t (*copy_file_range)(struct file *, loff_t, struct file *, loff_t, size_t, unsigned int);
int (*clone_file_range)(struct file *, loff_t, struct file *, loff_t, u64);
int (*dedupe_file_range)(struct file *, loff_t, struct file *, loff_t, u64);
int (*fadvise)(struct file *, loff_t, loff_t, int);
};
Again, all methods are called without any locks being held, unless
@ -899,6 +903,9 @@ otherwise noted.
iterate: called when the VFS needs to read the directory contents
iterate_shared: called when the VFS needs to read the directory contents
when filesystem supports concurrent dir iterators
poll: called by the VFS when a process wants to check if there is
activity on this file and (optionally) go to sleep until there
is activity. Called by the select(2) and poll(2) system calls
@ -951,6 +958,16 @@ otherwise noted.
fallocate: called by the VFS to preallocate blocks or punch a hole.
copy_file_range: called by the copy_file_range(2) system call.
clone_file_range: called by the ioctl(2) system call for FICLONERANGE and
FICLONE commands.
dedupe_file_range: called by the ioctl(2) system call for FIDEDUPERANGE
command.
fadvise: possibly called by the fadvise64() system call.
Note that the file operations are implemented by the specific
filesystem in which the inode resides. When opening a device node
(character or block special) most filesystems will call special

23
fs/overlayfs/file.c
View File

@ -131,9 +131,6 @@ static int ovl_open(struct inode *inode, struct file *file)
if (IS_ERR(realfile))
return PTR_ERR(realfile);
/* For O_DIRECT dentry_open() checks f_mapping->a_ops->direct_IO */
file->f_mapping = realfile->f_mapping;
file->private_data = realfile;
return 0;
@ -334,6 +331,25 @@ static long ovl_fallocate(struct file *file, int mode, loff_t offset, loff_t len
return ret;
}
static int ovl_fadvise(struct file *file, loff_t offset, loff_t len, int advice)
{
struct fd real;
const struct cred *old_cred;
int ret;
ret = ovl_real_fdget(file, &real);
if (ret)
return ret;
old_cred = ovl_override_creds(file_inode(file)->i_sb);
ret = vfs_fadvise(real.file, offset, len, advice);
revert_creds(old_cred);
fdput(real);
return ret;
}
static long ovl_real_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
@ -502,6 +518,7 @@ const struct file_operations ovl_file_operations = {
.fsync = ovl_fsync,
.mmap = ovl_mmap,
.fallocate = ovl_fallocate,
.fadvise = ovl_fadvise,
.unlocked_ioctl = ovl_ioctl,
.compat_ioctl = ovl_compat_ioctl,

10
fs/overlayfs/inode.c
View File

@ -467,6 +467,10 @@ static int ovl_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
return -EOPNOTSUPP;
old_cred = ovl_override_creds(inode->i_sb);
if (fieinfo->fi_flags & FIEMAP_FLAG_SYNC)
filemap_write_and_wait(realinode->i_mapping);
err = realinode->i_op->fiemap(realinode, fieinfo, start, len);
revert_creds(old_cred);
@ -500,6 +504,11 @@ static const struct inode_operations ovl_special_inode_operations = {
.update_time = ovl_update_time,
};
const struct address_space_operations ovl_aops = {
/* For O_DIRECT dentry_open() checks f_mapping->a_ops->direct_IO */
.direct_IO = noop_direct_IO,
};
/*
* It is possible to stack overlayfs instance on top of another
* overlayfs instance as lower layer. We need to annonate the
@ -571,6 +580,7 @@ static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev,
case S_IFREG:
inode->i_op = &ovl_file_inode_operations;
inode->i_fop = &ovl_file_operations;
inode->i_mapping->a_ops = &ovl_aops;
break;
case S_IFDIR:

26
fs/overlayfs/super.c
View File

@ -982,16 +982,6 @@ static int ovl_get_upper(struct ovl_fs *ofs, struct path *upperpath)
if (err)
goto out;
err = -EBUSY;
if (ovl_inuse_trylock(upperpath->dentry)) {
ofs->upperdir_locked = true;
} else if (ofs->config.index) {
pr_err("overlayfs: upperdir is in-use by another mount, mount with '-o index=off' to override exclusive upperdir protection.\n");
goto out;
} else {
pr_warn("overlayfs: upperdir is in-use by another mount, accessing files from both mounts will result in undefined behavior.\n");
}
upper_mnt = clone_private_mount(upperpath);
err = PTR_ERR(upper_mnt);
if (IS_ERR(upper_mnt)) {
@ -1002,6 +992,17 @@ static int ovl_get_upper(struct ovl_fs *ofs, struct path *upperpath)
/* Don't inherit atime flags */
upper_mnt->mnt_flags &= ~(MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME);
ofs->upper_mnt = upper_mnt;
err = -EBUSY;
if (ovl_inuse_trylock(ofs->upper_mnt->mnt_root)) {
ofs->upperdir_locked = true;
} else if (ofs->config.index) {
pr_err("overlayfs: upperdir is in-use by another mount, mount with '-o index=off' to override exclusive upperdir protection.\n");
goto out;
} else {
pr_warn("overlayfs: upperdir is in-use by another mount, accessing files from both mounts will result in undefined behavior.\n");
}
err = 0;
out:
return err;
@ -1101,8 +1102,10 @@ static int ovl_get_workdir(struct ovl_fs *ofs, struct path *upperpath)
goto out;
}
ofs->workbasedir = dget(workpath.dentry);
err = -EBUSY;
if (ovl_inuse_trylock(workpath.dentry)) {
if (ovl_inuse_trylock(ofs->workbasedir)) {
ofs->workdir_locked = true;
} else if (ofs->config.index) {
pr_err("overlayfs: workdir is in-use by another mount, mount with '-o index=off' to override exclusive workdir protection.\n");
@ -1111,7 +1114,6 @@ static int ovl_get_workdir(struct ovl_fs *ofs, struct path *upperpath)
pr_warn("overlayfs: workdir is in-use by another mount, accessing files from both mounts will result in undefined behavior.\n");
}
ofs->workbasedir = dget(workpath.dentry);
err = ovl_make_workdir(ofs, &workpath);
if (err)
goto out;

5
include/linux/fs.h
View File

@ -1763,6 +1763,7 @@ struct file_operations {
u64);
int (*dedupe_file_range)(struct file *, loff_t, struct file *, loff_t,
u64);
int (*fadvise)(struct file *, loff_t, loff_t, int);
} __randomize_layout;
struct inode_operations {
@ -3459,4 +3460,8 @@ static inline bool dir_relax_shared(struct inode *inode)
extern bool path_noexec(const struct path *path);
extern void inode_nohighmem(struct inode *inode);
/* mm/fadvise.c */
extern int vfs_fadvise(struct file *file, loff_t offset, loff_t len,
int advice);
#endif /* _LINUX_FS_H */

3
mm/Makefile
View File

@ -32,7 +32,7 @@ ifdef CONFIG_CROSS_MEMORY_ATTACH
mmu-$(CONFIG_MMU) += process_vm_access.o
endif
obj-y := filemap.o mempool.o oom_kill.o \
obj-y := filemap.o mempool.o oom_kill.o fadvise.o \
maccess.o page_alloc.o page-writeback.o \
readahead.o swap.o truncate.o vmscan.o shmem.o \
util.o mmzone.o vmstat.o backing-dev.o \
@ -49,7 +49,6 @@ else
obj-y += bootmem.o
endif
obj-$(CONFIG_ADVISE_SYSCALLS) += fadvise.o
ifdef CONFIG_MMU
obj-$(CONFIG_ADVISE_SYSCALLS) += madvise.o
endif

81
mm/fadvise.c
View File

@ -27,9 +27,9 @@
* deactivate the pages and clear PG_Referenced.
*/
int ksys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)
static int generic_fadvise(struct file *file, loff_t offset, loff_t len,
int advice)
{
struct fd f = fdget(fd);
struct inode *inode;
struct address_space *mapping;
struct backing_dev_info *bdi;
@ -37,22 +37,14 @@ int ksys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)
pgoff_t start_index;
pgoff_t end_index;
unsigned long nrpages;
int ret = 0;
if (!f.file)
return -EBADF;
inode = file_inode(file);
if (S_ISFIFO(inode->i_mode))
return -ESPIPE;
inode = file_inode(f.file);
if (S_ISFIFO(inode->i_mode)) {
ret = -ESPIPE;
goto out;
}
mapping = f.file->f_mapping;
if (!mapping || len < 0) {
ret = -EINVAL;
goto out;
}
mapping = file->f_mapping;
if (!mapping || len < 0)
return -EINVAL;
bdi = inode_to_bdi(mapping->host);
@ -67,9 +59,9 @@ int ksys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)
/* no bad return value, but ignore advice */
break;
default:
ret = -EINVAL;
return -EINVAL;
}
goto out;
return 0;
}
/*
@ -85,21 +77,21 @@ int ksys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)
switch (advice) {
case POSIX_FADV_NORMAL:
f.file->f_ra.ra_pages = bdi->ra_pages;
spin_lock(&f.file->f_lock);
f.file->f_mode &= ~FMODE_RANDOM;
spin_unlock(&f.file->f_lock);
file->f_ra.ra_pages = bdi->ra_pages;
spin_lock(&file->f_lock);
file->f_mode &= ~FMODE_RANDOM;
spin_unlock(&file->f_lock);
break;
case POSIX_FADV_RANDOM:
spin_lock(&f.file->f_lock);
f.file->f_mode |= FMODE_RANDOM;
spin_unlock(&f.file->f_lock);
spin_lock(&file->f_lock);
file->f_mode |= FMODE_RANDOM;
spin_unlock(&file->f_lock);
break;
case POSIX_FADV_SEQUENTIAL:
f.file->f_ra.ra_pages = bdi->ra_pages * 2;
spin_lock(&f.file->f_lock);
f.file->f_mode &= ~FMODE_RANDOM;
spin_unlock(&f.file->f_lock);
file->f_ra.ra_pages = bdi->ra_pages * 2;
spin_lock(&file->f_lock);
file->f_mode &= ~FMODE_RANDOM;
spin_unlock(&file->f_lock);
break;
case POSIX_FADV_WILLNEED:
/* First and last PARTIAL page! */
@ -115,8 +107,7 @@ int ksys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)
* Ignore return value because fadvise() shall return
* success even if filesystem can't retrieve a hint,
*/
force_page_cache_readahead(mapping, f.file, start_index,
nrpages);
force_page_cache_readahead(mapping, file, start_index, nrpages);
break;
case POSIX_FADV_NOREUSE:
break;
@ -183,9 +174,32 @@ int ksys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)
}
break;
default:
ret = -EINVAL;
return -EINVAL;
}
out:
return 0;
}
int vfs_fadvise(struct file *file, loff_t offset, loff_t len, int advice)
{
if (file->f_op->fadvise)
return file->f_op->fadvise(file, offset, len, advice);
return generic_fadvise(file, offset, len, advice);
}
EXPORT_SYMBOL(vfs_fadvise);
#ifdef CONFIG_ADVISE_SYSCALLS
int ksys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)
{
struct fd f = fdget(fd);
int ret;
if (!f.file)
return -EBADF;
ret = vfs_fadvise(f.file, offset, len, advice);
fdput(f);
return ret;
}
@ -203,3 +217,4 @@ SYSCALL_DEFINE4(fadvise64, int, fd, loff_t, offset, size_t, len, int, advice)
}
#endif
#endif

45
mm/readahead.c
View File

@ -20,6 +20,7 @@
#include <linux/file.h>
#include <linux/mm_inline.h>
#include <linux/blk-cgroup.h>
#include <linux/fadvise.h>
#include "internal.h"
@ -575,24 +576,6 @@ page_cache_async_readahead(struct address_space *mapping,
}
EXPORT_SYMBOL_GPL(page_cache_async_readahead);
static ssize_t
do_readahead(struct address_space *mapping, struct file *filp,
pgoff_t index, unsigned long nr)
{
if (!mapping || !mapping->a_ops)
return -EINVAL;
/*
* Readahead doesn't make sense for DAX inodes, but we don't want it
* to report a failure either. Instead, we just return success and
* don't do any work.
*/
if (dax_mapping(mapping))
return 0;
return force_page_cache_readahead(mapping, filp, index, nr);
}
ssize_t ksys_readahead(int fd, loff_t offset, size_t count)
{
ssize_t ret;
@ -600,16 +583,22 @@ ssize_t ksys_readahead(int fd, loff_t offset, size_t count)
ret = -EBADF;
f = fdget(fd);
if (f.file) {
if (f.file->f_mode & FMODE_READ) {
struct address_space *mapping = f.file->f_mapping;
pgoff_t start = offset >> PAGE_SHIFT;
pgoff_t end = (offset + count - 1) >> PAGE_SHIFT;
unsigned long len = end - start + 1;
ret = do_readahead(mapping, f.file, start, len);
}
fdput(f);
}
if (!f.file || !(f.file->f_mode & FMODE_READ))
goto out;
/*
* The readahead() syscall is intended to run only on files
* that can execute readahead. If readahead is not possible
* on this file, then we must return -EINVAL.
*/
ret = -EINVAL;
if (!f.file->f_mapping || !f.file->f_mapping->a_ops ||
!S_ISREG(file_inode(f.file)->i_mode))
goto out;
ret = vfs_fadvise(f.file, offset, count, POSIX_FADV_WILLNEED);
out:
fdput(f);
return ret;
}