Viewing: llite_mmap.c
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2004, 2010, Oracle and/or its affiliates. All rights reserved.
* Use is subject to license terms.
*
* Copyright (c) 2011, 2016, Intel Corporation.
*/
/*
* This file is part of Lustre, http://www.lustre.org/
*/
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/file.h>
#include <linux/kernel.h>
#include <linux/rwsem.h>
#include <linux/mm.h>
#include <lustre_compat/linux/mmap_lock.h>
#define DEBUG_SUBSYSTEM S_LLITE
#include "llite_internal.h"
static const struct vm_operations_struct ll_file_vm_ops;
void policy_from_vma(union ldlm_policy_data *policy, struct vm_area_struct *vma,
unsigned long addr, size_t bytes)
{
policy->l_extent.start = ((addr - vma->vm_start) & PAGE_MASK) +
(vma->vm_pgoff << PAGE_SHIFT);
policy->l_extent.end = (policy->l_extent.start + bytes - 1) |
~PAGE_MASK;
}
/*
* Linux commit v6.0-rc3-225-gf39af05949a4
* mm: add VMA iterator
*/
#ifndef VMA_ITERATOR
#define vma_iterator vm_area_struct *
#define vma_iter_init(vmip, mm, addr) *(vmip) = find_vma(mm, addr)
#define for_each_vma(vmi, vma) \
for (vma = vmi; vma != NULL; vma = vma->vm_next)
#endif
struct vm_area_struct *our_vma(struct mm_struct *mm, unsigned long addr,
size_t bytes)
{
struct vm_area_struct *vma, *ret = NULL;
struct vma_iterator vmi;
ENTRY;
/* mmap_lock must have been held by caller. */
LASSERT(!mmap_write_trylock(mm));
vma_iter_init(&vmi, mm, addr);
for_each_vma(vmi, vma) {
if (vma->vm_start < (addr + bytes))
break;
if (vma->vm_ops && vma->vm_ops == &ll_file_vm_ops &&
vma->vm_flags & VM_SHARED) {
ret = vma;
break;
}
}
RETURN(ret);
}
/**
* ll_fault_io_init() - API independent part for page fault initialization.
* @env: corespondent lu_env to processing
* @vma: virtual memory area addressed to page fault
* @index: page index corespondent to fault.
* @mkwrite: whether it is mmap write.
*
* Return:
* * pointer to a struct cl_io on success error otherwise
*/
static struct cl_io *
ll_fault_io_init(struct lu_env *env, struct vm_area_struct *vma,
pgoff_t index, bool mkwrite)
{
struct file *file = vma->vm_file;
struct inode *inode = file_inode(file);
struct cl_io *io;
struct cl_fault_io *fio;
int rc;
ENTRY;
if (ll_file_nolock(file))
RETURN(ERR_PTR(-EOPNOTSUPP));
restart:
io = vvp_env_new_io(env);
io->ci_obj = ll_i2info(inode)->lli_clob;
LASSERT(io->ci_obj != NULL);
fio = &io->u.ci_fault;
fio->ft_index = index;
fio->ft_executable = vma->vm_flags & VM_EXEC;
if (mkwrite) {
fio->ft_mkwrite = 1;
fio->ft_writable = 1;
}
if (vma->vm_flags & VM_SEQ_READ)
io->ci_seq_read = 1;
else if (vma->vm_flags & VM_RAND_READ)
io->ci_rand_read = 1;
rc = cl_io_init(env, io, CIT_FAULT, io->ci_obj);
if (rc == 0) {
struct vvp_io *vio = vvp_env_io(env);
struct ll_file_data *lfd = file->private_data;
LASSERT(vio->vui_cl.cis_io == io);
/* mmap lock must be MANDATORY it has to cache pages. */
io->ci_lockreq = CILR_MANDATORY;
vio->vui_fd = lfd;
} else {
cl_io_fini(env, io);
if (io->ci_need_restart)
goto restart;
io = ERR_PTR(rc);
}
RETURN(io);
}
static int __ll_page_mkwrite(struct vm_area_struct *vma, struct page *vmpage,
bool *retry)
{
struct lu_env *env;
struct cl_io *io;
struct vvp_io *vio;
int result;
__u16 refcheck;
sigset_t old, new;
struct inode *inode = NULL;
struct ll_inode_info *lli;
ENTRY;
LASSERT(vmpage != NULL);
env = cl_env_get(&refcheck);
if (IS_ERR(env))
RETURN(PTR_ERR(env));
io = ll_fault_io_init(env, vma, folio_index_page(vmpage), true);
if (IS_ERR(io))
GOTO(out, result = PTR_ERR(io));
result = io->ci_result;
if (result < 0)
GOTO(out_io, result);
vio = vvp_env_io(env);
vio->u.fault.ft_vma = vma;
vio->u.fault.ft_vmpage = vmpage;
siginitsetinv(&new, sigmask(SIGKILL) | sigmask(SIGTERM));
sigprocmask(SIG_BLOCK, &new, &old);
inode = vvp_object_inode(io->ci_obj);
lli = ll_i2info(inode);
result = cl_io_loop(env, io);
sigprocmask(SIG_SETMASK, &old, NULL);
if (result == 0) {
lock_page(vmpage);
if (vmpage->mapping == NULL) {
unlock_page(vmpage);
/* page was truncated and lock was cancelled, return
* ENODATA so that VM_FAULT_NOPAGE will be returned
* to handle_mm_fault().
*/
if (result == 0)
result = -ENODATA;
} else if (!PageDirty(vmpage)) {
/* race, the page has been cleaned by ptlrpcd after
* it was unlocked, it has to be added into dirty
* cache again otherwise this soon-to-dirty page won't
* consume any grants, even worse if this page is being
* transferred because it will break RPC checksum.
*/
unlock_page(vmpage);
CDEBUG(D_MMAP, "Race on page_mkwrite %p/%lu, page has been written out, retry.\n",
vmpage, folio_index_page(vmpage));
*retry = true;
result = -EAGAIN;
}
if (result == 0)
set_bit(LLIF_DATA_MODIFIED, &lli->lli_flags);
}
EXIT;
out_io:
cl_io_fini(env, io);
out:
cl_env_put(env, &refcheck);
CDEBUG(D_MMAP, "%s mkwrite with %d\n", current->comm, result);
LASSERT(ergo(result == 0, PageLocked(vmpage)));
/* if page has been unmapped, presumably due to lock reclaim for
* concurrent usage, add some delay before retrying to prevent
* entering live-lock situation with competitors
*/
if (result == -ENODATA && inode != NULL) {
CDEBUG(D_MMAP, "delaying new page-fault for inode %p to prevent live-lock\n",
inode);
msleep(10);
}
return result;
}
static inline int to_fault_error(int result)
{
switch (result) {
case 0:
result = VM_FAULT_LOCKED;
break;
case -ENOMEM:
result = VM_FAULT_OOM;
break;
default:
result = VM_FAULT_SIGBUS;
break;
}
return result;
}
int ll_filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct inode *inode = file_inode(vma->vm_file);
int ret;
unsigned int seq;
/* this seqlock lets us notice if a page has been deleted on this inode
* during the fault process, allowing us to catch an erroneous SIGBUS
* See LU-16160
*/
do {
seq = read_seqbegin(&ll_i2info(inode)->lli_page_inv_lock);
ret = filemap_fault(vmf);
} while (read_seqretry(&ll_i2info(inode)->lli_page_inv_lock, seq) &&
(ret & VM_FAULT_SIGBUS));
return ret;
}
/**
* __ll_fault() - Lustre implementation of a vm_operations_struct::fault()
* method, called by VM to server page fault (both in kernel and user space).
* @vma: is virtiual area struct related to page fault
* @vmf: structure which describe type and address where hit fault
*
* Return:
* * allocated and filled _locked_ page for address
* * VM_FAULT_ERROR on general error
* * NOPAGE_OOM not have memory for allocate new page
*/
static vm_fault_t __ll_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct inode *inode = file_inode(vma->vm_file);
struct lu_env *env;
struct cl_io *io;
struct vvp_io *vio = NULL;
struct page *vmpage;
int result = 0;
int fault_ret = 0;
__u16 refcheck;
ENTRY;
env = cl_env_get(&refcheck);
if (IS_ERR(env))
RETURN(PTR_ERR(env));
if (ll_sbi_has_fast_read(ll_i2sbi(inode))) {
/* do fast fault */
bool allow_retry = vmf->flags & FAULT_FLAG_ALLOW_RETRY;
bool has_retry = vmf->flags & FAULT_FLAG_RETRY_NOWAIT;
/* To avoid loops, instruct downstream to not drop mmap_sem */
/**
* only need FAULT_FLAG_ALLOW_RETRY prior to Linux 5.1
* (6b4c9f4469819), where FAULT_FLAG_RETRY_NOWAIT is enough
* to not drop mmap_sem when failed to lock the page.
*/
vmf->flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT;
ll_cl_add(inode, env, NULL, LCC_MMAP);
fault_ret = ll_filemap_fault(vma, vmf);
ll_cl_remove(inode, env);
if (!has_retry)
vmf->flags &= ~FAULT_FLAG_RETRY_NOWAIT;
if (!allow_retry)
vmf->flags &= ~FAULT_FLAG_ALLOW_RETRY;
/* - If there is no error, then the page was found in cache and
* uptodate;
* - If VM_FAULT_RETRY is set, the page existed but failed to
* lock. We will try slow path to avoid loops.
* - Otherwise, it should try normal fault under DLM lock.
*/
if (!(fault_ret & VM_FAULT_RETRY) &&
!(fault_ret & VM_FAULT_ERROR))
GOTO(out, result = 0);
fault_ret = 0;
}
io = ll_fault_io_init(env, vma, vmf->pgoff, false);
if (IS_ERR(io))
GOTO(out, result = PTR_ERR(io));
result = io->ci_result;
if (result == 0) {
vio = vvp_env_io(env);
vio->u.fault.ft_vma = vma;
vio->u.fault.ft_vmpage = NULL;
vio->u.fault.ft_vmf = vmf;
vio->u.fault.ft_flags = 0;
vio->u.fault.ft_flags_valid = 0;
/* May call ll_readpage() */
ll_cl_add(inode, env, io, LCC_MMAP);
result = cl_io_loop(env, io);
ll_cl_remove(inode, env);
/* ft_flags are only valid if we reached ll_filemap_fault() */
if (vio->u.fault.ft_flags_valid)
fault_ret = vio->u.fault.ft_flags;
vmpage = vio->u.fault.ft_vmpage;
if (result != 0 && vmpage != NULL) {
put_page(vmpage);
vmf->page = NULL;
}
}
cl_io_fini(env, io);
out:
cl_env_put(env, &refcheck);
if (result != 0 && !(fault_ret & VM_FAULT_RETRY))
fault_ret |= to_fault_error(result);
CDEBUG(D_MMAP, "%s fault %d/%d\n", current->comm, fault_ret, result);
RETURN(fault_ret);
}
static vm_fault_t ll_fault(struct vm_fault *vmf)
{
struct vm_area_struct *vma = vmf->vma;
int count = 0;
bool printed = false;
bool cached;
vm_fault_t result;
ktime_t kstart = ktime_get();
sigset_t old, new;
result = pcc_fault(vma, vmf, &cached);
if (cached)
return result;
CDEBUG(D_MMAP|D_IOTRACE,
"START file %s:"DFID", vma=%p start=%#lx end=%#lx vm_flags=%#lx idx=%lu vmf_flags=%#x\n",
file_dentry(vma->vm_file)->d_name.name,
PFID(&ll_i2info(file_inode(vma->vm_file))->lli_fid),
vma, vma->vm_start, vma->vm_end, vma->vm_flags, vmf->pgoff,
vmf->flags);
/* Only SIGKILL and SIGTERM is allowed for fault/nopage/mkwrite
* so that it can be killed by admin but not cause segfault by
* other signals.
*/
siginitsetinv(&new, sigmask(SIGKILL) | sigmask(SIGTERM));
sigprocmask(SIG_BLOCK, &new, &old);
/* make sure offset is not a negative number */
if (vmf->pgoff > (MAX_LFS_FILESIZE >> PAGE_SHIFT))
return VM_FAULT_SIGBUS;
restart:
result = __ll_fault(vma, vmf);
if (vmf->page &&
!(result & (VM_FAULT_RETRY | VM_FAULT_ERROR | VM_FAULT_LOCKED))) {
struct page *vmpage = vmf->page;
/* lock the page, then check if this page has been truncated
* or deleted from Lustre and retry if so
*/
lock_page(vmpage);
if (unlikely(vmpage->mapping == NULL) ||
vmpage->private == 0) { /* unlucky */
unlock_page(vmpage);
put_page(vmpage);
vmf->page = NULL;
if (!printed && ++count > 16) {
struct inode *inode = file_inode(vma->vm_file);
CWARN("%s: FID "DFID" under heavy mmap contention by '%s', consider revising IO pattern\n",
ll_i2sbi(inode)->ll_fsname,
PFID(&ll_i2info(inode)->lli_fid),
current->comm);
printed = true;
}
goto restart;
}
result |= VM_FAULT_LOCKED;
}
sigprocmask(SIG_SETMASK, &old, NULL);
if (vmf->page && result == VM_FAULT_LOCKED) {
ll_rw_stats_tally(ll_i2sbi(file_inode(vma->vm_file)),
current->pid, vma->vm_file->private_data,
vmf->pgoff << PAGE_SHIFT, PAGE_SIZE,
READ);
ll_stats_ops_tally(ll_i2sbi(file_inode(vma->vm_file)),
LPROC_LL_FAULT,
ktime_us_delta(ktime_get(), kstart));
}
CDEBUG(D_IOTRACE,
"COMPLETED: "DFID": vma=%p start=%#lx end=%#lx vm_flags=%#lx idx=%lu vmf_flags=%#x: rc=%d\n",
PFID(&ll_i2info(file_inode(vma->vm_file))->lli_fid),
vma, vma->vm_start, vma->vm_end, vma->vm_flags, vmf->pgoff,
vmf->flags, result);
return result;
}
static vm_fault_t ll_page_mkwrite(struct vm_fault *vmf)
{
struct vm_area_struct *vma = vmf->vma;
int count = 0;
bool printed = false;
bool retry;
bool cached;
ktime_t kstart = ktime_get();
vm_fault_t result;
CDEBUG(D_MMAP|D_IOTRACE,
"START file %s:"DFID", vma=%p start=%#lx end=%#lx vm_flags=%#lx idx=%lu\n",
file_dentry(vma->vm_file)->d_name.name,
PFID(&ll_i2info(file_inode(vma->vm_file))->lli_fid), vma,
vma->vm_start, vma->vm_end, vma->vm_flags, vmf->pgoff);
result = pcc_page_mkwrite(vma, vmf, &cached);
if (cached)
return result;
file_update_time(vma->vm_file);
do {
retry = false;
result = __ll_page_mkwrite(vma, vmf->page, &retry);
if (!printed && ++count > 16) {
const struct dentry *de = file_dentry(vma->vm_file);
CWARN("app(%s): the page %lu of file "DFID" is under heavy contention\n",
current->comm, vmf->pgoff,
PFID(ll_inode2fid(de->d_inode)));
printed = true;
}
} while (retry);
switch (result) {
case 0:
LASSERT(PageLocked(vmf->page));
result = VM_FAULT_LOCKED;
break;
case -ENODATA:
case -EFAULT:
result = VM_FAULT_NOPAGE;
break;
case -ENOMEM:
result = VM_FAULT_OOM;
break;
case -EAGAIN:
result = VM_FAULT_RETRY;
break;
default:
result = VM_FAULT_SIGBUS;
break;
}
if (result == VM_FAULT_LOCKED) {
ll_rw_stats_tally(ll_i2sbi(file_inode(vma->vm_file)),
current->pid, vma->vm_file->private_data,
vmf->pgoff << PAGE_SHIFT, PAGE_SIZE,
WRITE);
ll_stats_ops_tally(ll_i2sbi(file_inode(vma->vm_file)),
LPROC_LL_MKWRITE,
ktime_us_delta(ktime_get(), kstart));
}
CDEBUG(D_IOTRACE,
"COMPLETED: "DFID": vma=%p start=%#lx end=%#lx vm_flags=%#lx idx=%lu, rc %d\n",
PFID(&ll_i2info(file_inode(vma->vm_file))->lli_fid),
vma, vma->vm_start, vma->vm_end, vma->vm_flags,
vmf->pgoff, result);
return result;
}
/**
* ll_vm_open() - Called when VMA is being opened
* @vma: virtual memory area (VMA) structure that is being opened
*
* To avoid cancel the locks covering mmapped region for lock cache pressure,
* we track the mapped vma count in vvp_object::vob_mmap_cnt.
*/
static void ll_vm_open(struct vm_area_struct *vma)
{
ENTRY;
if (vma->vm_private_data == NULL) {
struct inode *inode = file_inode(vma->vm_file);
struct vvp_object *vob = cl_inode2vvp(inode);
LASSERT(atomic_read(&vob->vob_mmap_cnt) >= 0);
atomic_inc(&vob->vob_mmap_cnt);
} else {
pcc_vm_open(vma);
}
EXIT;
}
/**
* ll_vm_close() - Called when VMA is being closed(Dual to ll_vm_open())
* @vma: virtual memory area (VMA) structure that is being closed
*/
static void ll_vm_close(struct vm_area_struct *vma)
{
ENTRY;
if (vma->vm_private_data == NULL) {
struct inode *inode = file_inode(vma->vm_file);
struct vvp_object *vob = cl_inode2vvp(inode);
atomic_dec(&vob->vob_mmap_cnt);
LASSERT(atomic_read(&vob->vob_mmap_cnt) >= 0);
} else {
pcc_vm_close(vma);
}
EXIT;
}
static const struct vm_operations_struct ll_file_vm_ops = {
.fault = ll_fault,
.page_mkwrite = ll_page_mkwrite,
.open = ll_vm_open,
.close = ll_vm_close,
};
int ll_file_mmap(struct file *file, struct vm_area_struct *vma)
{
struct inode *inode = file_inode(file);
ktime_t kstart = ktime_get();
bool cached;
int rc;
ENTRY;
CDEBUG(D_VFSTRACE | D_MMAP,
"VFS_Op: fid="DFID" vma=%p start=%#lx end=%#lx vm_flags=%#lx\n",
PFID(&ll_i2info(inode)->lli_fid),
vma, vma->vm_start, vma->vm_end, vma->vm_flags);
if (ll_file_nolock(file))
RETURN(-EOPNOTSUPP);
rc = pcc_file_mmap(file, vma, &cached);
if (cached && rc != 0)
RETURN(rc);
rc = generic_file_mmap(file, vma);
if (rc == 0) {
vma->vm_ops = &ll_file_vm_ops;
vma->vm_ops->open(vma);
/* update the inode's size and mtime */
if (!cached)
rc = ll_glimpse_size(inode);
}
if (!rc)
ll_stats_ops_tally(ll_i2sbi(inode), LPROC_LL_MMAP,
ktime_us_delta(ktime_get(), kstart));
RETURN(rc);
}
