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sysfs: fix some bin_vm_ops errors

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Commit 86c9508eb1c0ce5aa07b5cf1d36b60c54efc3d7a
"sysfs: don't block indefinitely for unmapped files" in linux-next
crashes the PowerMac G5 when X starts up.  It's caught out by the way
powerpc's pci_mmap of legacy_mem uses shmem_zero_setup(), substituting
a new vma->vm_file whose private_data no longer points to the bin_buffer
(substitution done because some versions of X crash if that mmap fails).

The fix to this is straightforward: the original vm_file is fput() in
that case, so this mmap won't block sysfs at all, so just don't switch
over to bin_vm_ops if vm_file has changed.

But more fixes made before realizing that was the problem:-

It should not be an error if bin_page_mkwrite() finds no underlying
page_mkwrite().

Check that a file already mmap'ed has the same underlying vm_ops
_before_ pointing vma->vm_ops at bin_vm_ops.

If the file being mmap'ed is a shmem/tmpfs file, don't fail the mmap
on CONFIG_NUMA=y, just because that has a set_policy and get_policy:
provide bin_set_policy, bin_get_policy and bin_migrate.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Acked-by: Eric Biederman <ebiederm@aristanetworks.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Hugh Dickins 2009-03-23 01:41:27 +00:00 committed by Greg Kroah-Hartman
parent f520360d93
commit 095160aee9
1 changed files with 80 additions and 11 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

91
fs/sysfs/bin.c
View file

@ -241,9 +241,12 @@ static int bin_page_mkwrite(struct vm_area_struct *vma, struct page *page)
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
int ret;
if (!bb->vm_ops || !bb->vm_ops->page_mkwrite)
if (!bb->vm_ops)
return -EINVAL;
if (!bb->vm_ops->page_mkwrite)
return 0;
if (!sysfs_get_active_two(attr_sd))
return -EINVAL;
@ -273,12 +276,78 @@ static int bin_access(struct vm_area_struct *vma, unsigned long addr,
return ret;
}
#ifdef CONFIG_NUMA
static int bin_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
{
struct file *file = vma->vm_file;
struct bin_buffer *bb = file->private_data;
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
int ret;
if (!bb->vm_ops || !bb->vm_ops->set_policy)
return 0;
if (!sysfs_get_active_two(attr_sd))
return -EINVAL;
ret = bb->vm_ops->set_policy(vma, new);
sysfs_put_active_two(attr_sd);
return ret;
}
static struct mempolicy *bin_get_policy(struct vm_area_struct *vma,
unsigned long addr)
{
struct file *file = vma->vm_file;
struct bin_buffer *bb = file->private_data;
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
struct mempolicy *pol;
if (!bb->vm_ops || !bb->vm_ops->get_policy)
return vma->vm_policy;
if (!sysfs_get_active_two(attr_sd))
return vma->vm_policy;
pol = bb->vm_ops->get_policy(vma, addr);
sysfs_put_active_two(attr_sd);
return pol;
}
static int bin_migrate(struct vm_area_struct *vma, const nodemask_t *from,
const nodemask_t *to, unsigned long flags)
{
struct file *file = vma->vm_file;
struct bin_buffer *bb = file->private_data;
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
int ret;
if (!bb->vm_ops || !bb->vm_ops->migrate)
return 0;
if (!sysfs_get_active_two(attr_sd))
return 0;
ret = bb->vm_ops->migrate(vma, from, to, flags);
sysfs_put_active_two(attr_sd);
return ret;
}
#endif
static struct vm_operations_struct bin_vm_ops = {
.open = bin_vma_open,
.close = bin_vma_close,
.fault = bin_fault,
.page_mkwrite = bin_page_mkwrite,
.access = bin_access,
#ifdef CONFIG_NUMA
.set_policy = bin_set_policy,
.get_policy = bin_get_policy,
.migrate = bin_migrate,
#endif
};
static int mmap(struct file *file, struct vm_area_struct *vma)
@ -287,7 +356,6 @@ static int mmap(struct file *file, struct vm_area_struct *vma)
struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
struct vm_operations_struct *vm_ops;
int rc;
mutex_lock(&bb->mutex);
@ -302,24 +370,25 @@ static int mmap(struct file *file, struct vm_area_struct *vma)
goto out_put;
rc = attr->mmap(kobj, attr, vma);
vm_ops = vma->vm_ops;
vma->vm_ops = &bin_vm_ops;
if (rc)
goto out_put;
/*
* PowerPC's pci_mmap of legacy_mem uses shmem_zero_setup()
* to satisfy versions of X which crash if the mmap fails: that
* substitutes a new vm_file, and we don't then want bin_vm_ops.
*/
if (vma->vm_file != file)
goto out_put;
rc = -EINVAL;
if (bb->mmapped && bb->vm_ops != vma->vm_ops)
goto out_put;
#ifdef CONFIG_NUMA
rc = -EINVAL;
if (vm_ops && ((vm_ops->set_policy || vm_ops->get_policy || vm_ops->migrate)))
goto out_put;
#endif
rc = 0;
bb->mmapped = 1;
bb->vm_ops = vm_ops;
bb->vm_ops = vma->vm_ops;
vma->vm_ops = &bin_vm_ops;
out_put:
sysfs_put_active_two(attr_sd);
out_unlock: