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Merge branch 'libnvdimm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm

Browse Source 
Pull DAX updates from Dan Williams:
 "The completion of Jan's DAX work for 4.10.

  As I mentioned in the libnvdimm-for-4.10 pull request, these are some
  final fixes for the DAX dirty-cacheline-tracking invalidation work
  that was merged through the -mm, ext4, and xfs trees in -rc1. These
  patches were prepared prior to the merge window, but we waited for
  4.10-rc1 to have a stable merge base after all the prerequisites were
  merged.

  Quoting Jan on the overall changes in these patches:

     "So I'd like all these 6 patches to go for rc2. The first three
      patches fix invalidation of exceptional DAX entries (a bug which
      is there for a long time) - without these patches data loss can
      occur on power failure even though user called fsync(2). The other
      three patches change locking of DAX faults so that ->iomap_begin()
      is called in a more relaxed locking context and we are safe to
      start a transaction there for ext4"

  These have received a build success notification from the kbuild
  robot, and pass the latest libnvdimm unit tests. There have not been
  any -next releases since -rc1, so they have not appeared there"

* 'libnvdimm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  ext4: Simplify DAX fault path
  dax: Call ->iomap_begin without entry lock during dax fault
  dax: Finish fault completely when loading holes
  dax: Avoid page invalidation races and unnecessary radix tree traversals
  mm: Invalidate DAX radix tree entries only if appropriate
  ext2: Return BH_New buffers for zeroed blocks
tirimbino
Linus Torvalds 8 years ago
parent 238d1d0f79 1db175428e
commit 4759d386d5
5 changed files with 229 additions and 143 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Show Stats Download Patch File Download Diff File
  1. 243
      fs/dax.c
  2. 3
      fs/ext2/inode.c
  3. 48
      fs/ext4/file.c
  4. 3
      include/linux/dax.h
  5. 75
      mm/truncate.c

243
fs/dax.c
Unescape View File

@ -451,16 +451,37 @@ void dax_wake_mapping_entry_waiter(struct address_space *mapping,
__wake_up(wq, TASK_NORMAL, wake_all ? 0 : 1, &key);
}
static int __dax_invalidate_mapping_entry(struct address_space *mapping,
pgoff_t index, bool trunc)
{
int ret = 0;
void *entry;
struct radix_tree_root *page_tree = &mapping->page_tree;
spin_lock_irq(&mapping->tree_lock);
entry = get_unlocked_mapping_entry(mapping, index, NULL);
if (!entry || !radix_tree_exceptional_entry(entry))
goto out;
if (!trunc &&
(radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_DIRTY) ||
radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE)))
goto out;
radix_tree_delete(page_tree, index);
mapping->nrexceptional--;
ret = 1;
out:
put_unlocked_mapping_entry(mapping, index, entry);
spin_unlock_irq(&mapping->tree_lock);
return ret;
}
/*
* Delete exceptional DAX entry at @index from @mapping. Wait for radix tree
* entry to get unlocked before deleting it.
*/
int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index)
{
void *entry;
int ret = __dax_invalidate_mapping_entry(mapping, index, true);
spin_lock_irq(&mapping->tree_lock);
entry = get_unlocked_mapping_entry(mapping, index, NULL);
/*
* This gets called from truncate / punch_hole path. As such, the caller
* must hold locks protecting against concurrent modifications of the
@ -468,16 +489,46 @@ int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index)
* caller has seen exceptional entry for this index, we better find it
* at that index as well...
*/
if (WARN_ON_ONCE(!entry || !radix_tree_exceptional_entry(entry))) {
spin_unlock_irq(&mapping->tree_lock);
return 0;
}
radix_tree_delete(&mapping->page_tree, index);
WARN_ON_ONCE(!ret);
return ret;
}
/*
* Invalidate exceptional DAX entry if easily possible. This handles DAX
* entries for invalidate_inode_pages() so we evict the entry only if we can
* do so without blocking.
*/
int dax_invalidate_mapping_entry(struct address_space *mapping, pgoff_t index)
{
int ret = 0;
void *entry, **slot;
struct radix_tree_root *page_tree = &mapping->page_tree;
spin_lock_irq(&mapping->tree_lock);
entry = __radix_tree_lookup(page_tree, index, NULL, &slot);
if (!entry || !radix_tree_exceptional_entry(entry) ||
slot_locked(mapping, slot))
goto out;
if (radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_DIRTY) ||
radix_tree_tag_get(page_tree, index, PAGECACHE_TAG_TOWRITE))
goto out;
radix_tree_delete(page_tree, index);
mapping->nrexceptional--;
ret = 1;
out:
spin_unlock_irq(&mapping->tree_lock);
dax_wake_mapping_entry_waiter(mapping, index, entry, true);
if (ret)
dax_wake_mapping_entry_waiter(mapping, index, entry, true);
return ret;
}
return 1;
/*
* Invalidate exceptional DAX entry if it is clean.
*/
int dax_invalidate_mapping_entry_sync(struct address_space *mapping,
pgoff_t index)
{
return __dax_invalidate_mapping_entry(mapping, index, false);
}
/*
@ -488,15 +539,16 @@ int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index)
* otherwise it will simply fall out of the page cache under memory
* pressure without ever having been dirtied.
*/
static int dax_load_hole(struct address_space *mapping, void *entry,
static int dax_load_hole(struct address_space *mapping, void **entry,
struct vm_fault *vmf)
{
struct page *page;
int ret;
/* Hole page already exists? Return it... */
if (!radix_tree_exceptional_entry(entry)) {
vmf->page = entry;
return VM_FAULT_LOCKED;
if (!radix_tree_exceptional_entry(*entry)) {
page = *entry;
goto out;
}
/* This will replace locked radix tree entry with a hole page */
@ -504,8 +556,17 @@ static int dax_load_hole(struct address_space *mapping, void *entry,
vmf->gfp_mask | __GFP_ZERO);
if (!page)
return VM_FAULT_OOM;
out:
vmf->page = page;
return VM_FAULT_LOCKED;
ret = finish_fault(vmf);
vmf->page = NULL;
*entry = page;
if (!ret) {
/* Grab reference for PTE that is now referencing the page */
get_page(page);
return VM_FAULT_NOPAGE;
}
return ret;
}
static int copy_user_dax(struct block_device *bdev, sector_t sector, size_t size,
@ -934,6 +995,17 @@ dax_iomap_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
if (WARN_ON_ONCE(iomap->type != IOMAP_MAPPED))
return -EIO;
/*
* Write can allocate block for an area which has a hole page mapped
* into page tables. We have to tear down these mappings so that data
* written by write(2) is visible in mmap.
*/
if ((iomap->flags & IOMAP_F_NEW) && inode->i_mapping->nrpages) {
invalidate_inode_pages2_range(inode->i_mapping,
pos >> PAGE_SHIFT,
(end - 1) >> PAGE_SHIFT);
}
while (pos < end) {
unsigned offset = pos & (PAGE_SIZE - 1);
struct blk_dax_ctl dax = { 0 };
@ -992,23 +1064,6 @@ dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter,
if (iov_iter_rw(iter) == WRITE)
flags |= IOMAP_WRITE;
/*
* Yes, even DAX files can have page cache attached to them: A zeroed
* page is inserted into the pagecache when we have to serve a write
* fault on a hole. It should never be dirtied and can simply be
* dropped from the pagecache once we get real data for the page.
*
* XXX: This is racy against mmap, and there's nothing we can do about
* it. We'll eventually need to shift this down even further so that
* we can check if we allocated blocks over a hole first.
*/
if (mapping->nrpages) {
ret = invalidate_inode_pages2_range(mapping,
pos >> PAGE_SHIFT,
(pos + iov_iter_count(iter) - 1) >> PAGE_SHIFT);
WARN_ON_ONCE(ret);
}
while (iov_iter_count(iter)) {
ret = iomap_apply(inode, pos, iov_iter_count(iter), flags, ops,
iter, dax_iomap_actor);
@ -1023,6 +1078,15 @@ dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter,
}
EXPORT_SYMBOL_GPL(dax_iomap_rw);
static int dax_fault_return(int error)
{
if (error == 0)
return VM_FAULT_NOPAGE;
if (error == -ENOMEM)
return VM_FAULT_OOM;
return VM_FAULT_SIGBUS;
}
/**
* dax_iomap_fault - handle a page fault on a DAX file
* @vma: The virtual memory area where the fault occurred
@ -1055,12 +1119,6 @@ int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
if (pos >= i_size_read(inode))
return VM_FAULT_SIGBUS;
entry = grab_mapping_entry(mapping, vmf->pgoff, 0);
if (IS_ERR(entry)) {
error = PTR_ERR(entry);
goto out;
}
if ((vmf->flags & FAULT_FLAG_WRITE) && !vmf->cow_page)
flags |= IOMAP_WRITE;
@ -1071,9 +1129,15 @@ int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
*/
error = ops->iomap_begin(inode, pos, PAGE_SIZE, flags, &iomap);
if (error)
goto unlock_entry;
return dax_fault_return(error);
if (WARN_ON_ONCE(iomap.offset + iomap.length < pos + PAGE_SIZE)) {
error = -EIO; /* fs corruption? */
vmf_ret = dax_fault_return(-EIO); /* fs corruption? */
goto finish_iomap;
}
entry = grab_mapping_entry(mapping, vmf->pgoff, 0);
if (IS_ERR(entry)) {
vmf_ret = dax_fault_return(PTR_ERR(entry));
goto finish_iomap;
}
@ -1096,13 +1160,13 @@ int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
}
if (error)
goto finish_iomap;
goto error_unlock_entry;
__SetPageUptodate(vmf->cow_page);
vmf_ret = finish_fault(vmf);
if (!vmf_ret)
vmf_ret = VM_FAULT_DONE_COW;
goto finish_iomap;
goto unlock_entry;
}
switch (iomap.type) {
@ -1114,12 +1178,15 @@ int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
}
error = dax_insert_mapping(mapping, iomap.bdev, sector,
PAGE_SIZE, &entry, vma, vmf);
/* -EBUSY is fine, somebody else faulted on the same PTE */
if (error == -EBUSY)
error = 0;
break;
case IOMAP_UNWRITTEN:
case IOMAP_HOLE:
if (!(vmf->flags & FAULT_FLAG_WRITE)) {
vmf_ret = dax_load_hole(mapping, entry, vmf);
break;
vmf_ret = dax_load_hole(mapping, &entry, vmf);
goto unlock_entry;
}
/*FALLTHRU*/
default:
@ -1128,31 +1195,25 @@ int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
break;
}
error_unlock_entry:
vmf_ret = dax_fault_return(error) | major;
unlock_entry:
put_locked_mapping_entry(mapping, vmf->pgoff, entry);
finish_iomap:
if (ops->iomap_end) {
if (error || (vmf_ret & VM_FAULT_ERROR)) {
/* keep previous error */
ops->iomap_end(inode, pos, PAGE_SIZE, 0, flags,
&iomap);
} else {
error = ops->iomap_end(inode, pos, PAGE_SIZE,
PAGE_SIZE, flags, &iomap);
}
}
unlock_entry:
if (vmf_ret != VM_FAULT_LOCKED || error)
put_locked_mapping_entry(mapping, vmf->pgoff, entry);
out:
if (error == -ENOMEM)
return VM_FAULT_OOM | major;
/* -EBUSY is fine, somebody else faulted on the same PTE */
if (error < 0 && error != -EBUSY)
return VM_FAULT_SIGBUS | major;
if (vmf_ret) {
WARN_ON_ONCE(error); /* -EBUSY from ops->iomap_end? */
return vmf_ret;
int copied = PAGE_SIZE;
if (vmf_ret & VM_FAULT_ERROR)
copied = 0;
/*
* The fault is done by now and there's no way back (other
* thread may be already happily using PTE we have installed).
* Just ignore error from ->iomap_end since we cannot do much
* with it.
*/
ops->iomap_end(inode, pos, PAGE_SIZE, copied, flags, &iomap);
}
return VM_FAULT_NOPAGE | major;
return vmf_ret;
}
EXPORT_SYMBOL_GPL(dax_iomap_fault);
@ -1276,16 +1337,6 @@ int dax_iomap_pmd_fault(struct vm_area_struct *vma, unsigned long address,
if ((pgoff | PG_PMD_COLOUR) > max_pgoff)
goto fallback;
/*
* grab_mapping_entry() will make sure we get a 2M empty entry, a DAX
* PMD or a HZP entry. If it can't (because a 4k page is already in
* the tree, for instance), it will return -EEXIST and we just fall
* back to 4k entries.
*/
entry = grab_mapping_entry(mapping, pgoff, RADIX_DAX_PMD);
if (IS_ERR(entry))
goto fallback;
/*
* Note that we don't use iomap_apply here. We aren't doing I/O, only
* setting up a mapping, so really we're using iomap_begin() as a way
@ -1294,10 +1345,21 @@ int dax_iomap_pmd_fault(struct vm_area_struct *vma, unsigned long address,
pos = (loff_t)pgoff << PAGE_SHIFT;
error = ops->iomap_begin(inode, pos, PMD_SIZE, iomap_flags, &iomap);
if (error)
goto unlock_entry;
goto fallback;
if (iomap.offset + iomap.length < pos + PMD_SIZE)
goto finish_iomap;
/*
* grab_mapping_entry() will make sure we get a 2M empty entry, a DAX
* PMD or a HZP entry. If it can't (because a 4k page is already in
* the tree, for instance), it will return -EEXIST and we just fall
* back to 4k entries.
*/
entry = grab_mapping_entry(mapping, pgoff, RADIX_DAX_PMD);
if (IS_ERR(entry))
goto finish_iomap;
vmf.pgoff = pgoff;
vmf.flags = flags;
vmf.gfp_mask = mapping_gfp_mask(mapping) | __GFP_IO;
@ -1310,7 +1372,7 @@ int dax_iomap_pmd_fault(struct vm_area_struct *vma, unsigned long address,
case IOMAP_UNWRITTEN:
case IOMAP_HOLE:
if (WARN_ON_ONCE(write))
goto finish_iomap;
goto unlock_entry;
result = dax_pmd_load_hole(vma, pmd, &vmf, address, &iomap,
&entry);
break;
@ -1319,20 +1381,23 @@ int dax_iomap_pmd_fault(struct vm_area_struct *vma, unsigned long address,
break;
}
unlock_entry:
put_locked_mapping_entry(mapping, pgoff, entry);
finish_iomap:
if (ops->iomap_end) {
if (result == VM_FAULT_FALLBACK) {
ops->iomap_end(inode, pos, PMD_SIZE, 0, iomap_flags,
&iomap);
} else {
error = ops->iomap_end(inode, pos, PMD_SIZE, PMD_SIZE,
iomap_flags, &iomap);
if (error)
result = VM_FAULT_FALLBACK;
}
int copied = PMD_SIZE;
if (result == VM_FAULT_FALLBACK)
copied = 0;
/*
* The fault is done by now and there's no way back (other
* thread may be already happily using PMD we have installed).
* Just ignore error from ->iomap_end since we cannot do much
* with it.
*/
ops->iomap_end(inode, pos, PMD_SIZE, copied, iomap_flags,
&iomap);
}
unlock_entry:
put_locked_mapping_entry(mapping, pgoff, entry);
fallback:
if (result == VM_FAULT_FALLBACK) {
split_huge_pmd(vma, pmd, address);

3
fs/ext2/inode.c
Unescape View File

@ -751,9 +751,8 @@ static int ext2_get_blocks(struct inode *inode,
mutex_unlock(&ei->truncate_mutex);
goto cleanup;
}
} else {
*new = true;
}
*new = true;
ext2_splice_branch(inode, iblock, partial, indirect_blks, count);
mutex_unlock(&ei->truncate_mutex);

48
fs/ext4/file.c
Unescape View File

@ -258,7 +258,6 @@ out:
static int ext4_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
int result;
handle_t *handle = NULL;
struct inode *inode = file_inode(vma->vm_file);
struct super_block *sb = inode->i_sb;
bool write = vmf->flags & FAULT_FLAG_WRITE;
@ -266,24 +265,12 @@ static int ext4_dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
if (write) {
sb_start_pagefault(sb);
file_update_time(vma->vm_file);
down_read(&EXT4_I(inode)->i_mmap_sem);
handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
EXT4_DATA_TRANS_BLOCKS(sb));
} else
down_read(&EXT4_I(inode)->i_mmap_sem);
if (IS_ERR(handle))
result = VM_FAULT_SIGBUS;
else
result = dax_iomap_fault(vma, vmf, &ext4_iomap_ops);
if (write) {
if (!IS_ERR(handle))
ext4_journal_stop(handle);
up_read(&EXT4_I(inode)->i_mmap_sem);
}
down_read(&EXT4_I(inode)->i_mmap_sem);
result = dax_iomap_fault(vma, vmf, &ext4_iomap_ops);
up_read(&EXT4_I(inode)->i_mmap_sem);
if (write)
sb_end_pagefault(sb);
} else
up_read(&EXT4_I(inode)->i_mmap_sem);
return result;
}
@ -292,7 +279,6 @@ static int ext4_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
pmd_t *pmd, unsigned int flags)
{
int result;
handle_t *handle = NULL;
struct inode *inode = file_inode(vma->vm_file);
struct super_block *sb = inode->i_sb;
bool write = flags & FAULT_FLAG_WRITE;
@ -300,27 +286,13 @@ static int ext4_dax_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
if (write) {
sb_start_pagefault(sb);
file_update_time(vma->vm_file);
down_read(&EXT4_I(inode)->i_mmap_sem);
handle = ext4_journal_start_sb(sb, EXT4_HT_WRITE_PAGE,
ext4_chunk_trans_blocks(inode,
PMD_SIZE / PAGE_SIZE));
} else
down_read(&EXT4_I(inode)->i_mmap_sem);
if (IS_ERR(handle))
result = VM_FAULT_SIGBUS;
else {
result = dax_iomap_pmd_fault(vma, addr, pmd, flags,
&ext4_iomap_ops);
}
if (write) {
if (!IS_ERR(handle))
ext4_journal_stop(handle);
up_read(&EXT4_I(inode)->i_mmap_sem);
down_read(&EXT4_I(inode)->i_mmap_sem);
result = dax_iomap_pmd_fault(vma, addr, pmd, flags,
&ext4_iomap_ops);
up_read(&EXT4_I(inode)->i_mmap_sem);
if (write)
sb_end_pagefault(sb);
} else
up_read(&EXT4_I(inode)->i_mmap_sem);
return result;
}

3
include/linux/dax.h
Unescape View File

@ -41,6 +41,9 @@ ssize_t dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter,
int dax_iomap_fault(struct vm_area_struct *vma, struct vm_fault *vmf,
struct iomap_ops *ops);
int dax_delete_mapping_entry(struct address_space *mapping, pgoff_t index);
int dax_invalidate_mapping_entry(struct address_space *mapping, pgoff_t index);
int dax_invalidate_mapping_entry_sync(struct address_space *mapping,
pgoff_t index);
void dax_wake_mapping_entry_waiter(struct address_space *mapping,
pgoff_t index, void *entry, bool wake_all);

75
mm/truncate.c
Unescape View File

@ -24,20 +24,12 @@
#include <linux/rmap.h>
#include "internal.h"
static void clear_exceptional_entry(struct address_space *mapping,
pgoff_t index, void *entry)
static void clear_shadow_entry(struct address_space *mapping, pgoff_t index,
void *entry)
{
struct radix_tree_node *node;
void **slot;
/* Handled by shmem itself */
if (shmem_mapping(mapping))
return;
if (dax_mapping(mapping)) {
dax_delete_mapping_entry(mapping, index);
return;
}
spin_lock_irq(&mapping->tree_lock);
/*
* Regular page slots are stabilized by the page lock even
@ -55,6 +47,56 @@ unlock:
spin_unlock_irq(&mapping->tree_lock);
}
/*
* Unconditionally remove exceptional entry. Usually called from truncate path.
*/
static void truncate_exceptional_entry(struct address_space *mapping,
pgoff_t index, void *entry)
{
/* Handled by shmem itself */
if (shmem_mapping(mapping))
return;
if (dax_mapping(mapping)) {
dax_delete_mapping_entry(mapping, index);
return;
}
clear_shadow_entry(mapping, index, entry);
}
/*
* Invalidate exceptional entry if easily possible. This handles exceptional
* entries for invalidate_inode_pages() so for DAX it evicts only unlocked and
* clean entries.
*/
static int invalidate_exceptional_entry(struct address_space *mapping,
pgoff_t index, void *entry)
{
/* Handled by shmem itself */
if (shmem_mapping(mapping))
return 1;
if (dax_mapping(mapping))
return dax_invalidate_mapping_entry(mapping, index);
clear_shadow_entry(mapping, index, entry);
return 1;
}
/*
* Invalidate exceptional entry if clean. This handles exceptional entries for
* invalidate_inode_pages2() so for DAX it evicts only clean entries.
*/
static int invalidate_exceptional_entry2(struct address_space *mapping,
pgoff_t index, void *entry)
{
/* Handled by shmem itself */
if (shmem_mapping(mapping))
return 1;
if (dax_mapping(mapping))
return dax_invalidate_mapping_entry_sync(mapping, index);
clear_shadow_entry(mapping, index, entry);
return 1;
}
/**
* do_invalidatepage - invalidate part or all of a page
* @page: the page which is affected
@ -262,7 +304,8 @@ void truncate_inode_pages_range(struct address_space *mapping,
break;
if (radix_tree_exceptional_entry(page)) {
clear_exceptional_entry(mapping, index, page);
truncate_exceptional_entry(mapping, index,
page);
continue;
}
@ -351,7 +394,8 @@ void truncate_inode_pages_range(struct address_space *mapping,
}
if (radix_tree_exceptional_entry(page)) {
clear_exceptional_entry(mapping, index, page);
truncate_exceptional_entry(mapping, index,
page);
continue;
}
@ -470,7 +514,8 @@ unsigned long invalidate_mapping_pages(struct address_space *mapping,
break;
if (radix_tree_exceptional_entry(page)) {
clear_exceptional_entry(mapping, index, page);
invalidate_exceptional_entry(mapping, index,
page);
continue;
}
@ -592,7 +637,9 @@ int invalidate_inode_pages2_range(struct address_space *mapping,
break;
if (radix_tree_exceptional_entry(page)) {
clear_exceptional_entry(mapping, index, page);
if (!invalidate_exceptional_entry2(mapping,
index, page))
ret = -EBUSY;
continue;
}

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