Revision a742994aa2e271eb8cd8e043d276515ec858ed73 authored by Filipe Manana on 13 February 2015, 16:56:14 UTC, committed by Chris Mason on 14 February 2015, 16:22:49 UTC
If we are recording in the tree log that an inode has new names (new hard
links were added), we would drop items, belonging to the inode, that we
shouldn't:
1) When the flag BTRFS_INODE_COPY_EVERYTHING is set in the inode's runtime
flags, we ended up dropping all the extent and xattr items that were
previously logged. This was done only in memory, since logging a new
name doesn't imply syncing the log;
2) When the flag BTRFS_INODE_COPY_EVERYTHING is set in the inode's runtime
flags, we ended up dropping all the xattr items that were previously
logged. Like the case before, this was done only in memory because
logging a new name doesn't imply syncing the log.
This led to some surprises in scenarios such as the following:
1) write some extents to an inode;
2) fsync the inode;
3) truncate the inode or delete/modify some of its xattrs
4) add a new hard link for that inode
5) fsync some other file, to force the log tree to be durably persisted
6) power failure happens
The next time the fs is mounted, the fsync log replay code is executed,
and the resulting file doesn't have the content it had when the last fsync
against it was performed, instead if has a content matching what it had
when the last transaction commit happened.
So change the behaviour such that when a new name is logged, only the inode
item and reference items are processed.
This is easy to reproduce with the test I just made for xfstests, whose
main body is:
_scratch_mkfs >> $seqres.full 2>&1
_init_flakey
_mount_flakey
# Create our test file with some data.
$XFS_IO_PROG -f -c "pwrite -S 0xaa -b 8K 0 8K" \
$SCRATCH_MNT/foo | _filter_xfs_io
# Make sure the file is durably persisted.
sync
# Append some data to our file, to increase its size.
$XFS_IO_PROG -f -c "pwrite -S 0xcc -b 4K 8K 4K" \
$SCRATCH_MNT/foo | _filter_xfs_io
# Fsync the file, so from this point on if a crash/power failure happens, our
# new data is guaranteed to be there next time the fs is mounted.
$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/foo
# Now shrink our file to 5000 bytes.
$XFS_IO_PROG -c "truncate 5000" $SCRATCH_MNT/foo
# Now do an expanding truncate to a size larger than what we had when we last
# fsync'ed our file. This is just to verify that after power failure and
# replaying the fsync log, our file matches what it was when we last fsync'ed
# it - 12Kb size, first 8Kb of data had a value of 0xaa and the last 4Kb of
# data had a value of 0xcc.
$XFS_IO_PROG -c "truncate 32K" $SCRATCH_MNT/foo
# Add one hard link to our file. This made btrfs drop all of our file's
# metadata from the fsync log, including the metadata relative to the
# extent we just wrote and fsync'ed. This change was made only to the fsync
# log in memory, so adding the hard link alone doesn't change the persisted
# fsync log. This happened because the previous truncates set the runtime
# flag BTRFS_INODE_NEEDS_FULL_SYNC in the btrfs inode structure.
ln $SCRATCH_MNT/foo $SCRATCH_MNT/foo_link
# Now make sure the in memory fsync log is durably persisted.
# Creating and fsync'ing another file will do it.
# After this our persisted fsync log will no longer have metadata for our file
# foo that points to the extent we wrote and fsync'ed before.
touch $SCRATCH_MNT/bar
$XFS_IO_PROG -c "fsync" $SCRATCH_MNT/bar
# As expected, before the crash/power failure, we should be able to see a file
# with a size of 32Kb, with its first 5000 bytes having the value 0xaa and all
# the remaining bytes with value 0x00.
echo "File content before:"
od -t x1 $SCRATCH_MNT/foo
# Simulate a crash/power loss.
_load_flakey_table $FLAKEY_DROP_WRITES
_unmount_flakey
_load_flakey_table $FLAKEY_ALLOW_WRITES
_mount_flakey
# After mounting the fs again, the fsync log was replayed.
# The expected result is to see a file with a size of 12Kb, with its first 8Kb
# of data having the value 0xaa and its last 4Kb of data having a value of 0xcc.
# The btrfs bug used to leave the file as it used te be as of the last
# transaction commit - that is, with a size of 8Kb with all bytes having a
# value of 0xaa.
echo "File content after:"
od -t x1 $SCRATCH_MNT/foo
The test case for xfstests follows soon.
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
1 parent 1a4bcf4
pgtable.h
#ifndef _ASM_GENERIC_PGTABLE_H
#define _ASM_GENERIC_PGTABLE_H
#ifndef __ASSEMBLY__
#ifdef CONFIG_MMU
#include <linux/mm_types.h>
#include <linux/bug.h>
/*
* On almost all architectures and configurations, 0 can be used as the
* upper ceiling to free_pgtables(): on many architectures it has the same
* effect as using TASK_SIZE. However, there is one configuration which
* must impose a more careful limit, to avoid freeing kernel pgtables.
*/
#ifndef USER_PGTABLES_CEILING
#define USER_PGTABLES_CEILING 0UL
#endif
#ifndef __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
extern int ptep_set_access_flags(struct vm_area_struct *vma,
unsigned long address, pte_t *ptep,
pte_t entry, int dirty);
#endif
#ifndef __HAVE_ARCH_PMDP_SET_ACCESS_FLAGS
extern int pmdp_set_access_flags(struct vm_area_struct *vma,
unsigned long address, pmd_t *pmdp,
pmd_t entry, int dirty);
#endif
#ifndef __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
static inline int ptep_test_and_clear_young(struct vm_area_struct *vma,
unsigned long address,
pte_t *ptep)
{
pte_t pte = *ptep;
int r = 1;
if (!pte_young(pte))
r = 0;
else
set_pte_at(vma->vm_mm, address, ptep, pte_mkold(pte));
return r;
}
#endif
#ifndef __HAVE_ARCH_PMDP_TEST_AND_CLEAR_YOUNG
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma,
unsigned long address,
pmd_t *pmdp)
{
pmd_t pmd = *pmdp;
int r = 1;
if (!pmd_young(pmd))
r = 0;
else
set_pmd_at(vma->vm_mm, address, pmdp, pmd_mkold(pmd));
return r;
}
#else /* CONFIG_TRANSPARENT_HUGEPAGE */
static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma,
unsigned long address,
pmd_t *pmdp)
{
BUG();
return 0;
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
#endif
#ifndef __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH
int ptep_clear_flush_young(struct vm_area_struct *vma,
unsigned long address, pte_t *ptep);
#endif
#ifndef __HAVE_ARCH_PMDP_CLEAR_YOUNG_FLUSH
int pmdp_clear_flush_young(struct vm_area_struct *vma,
unsigned long address, pmd_t *pmdp);
#endif
#ifndef __HAVE_ARCH_PTEP_GET_AND_CLEAR
static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
unsigned long address,
pte_t *ptep)
{
pte_t pte = *ptep;
pte_clear(mm, address, ptep);
return pte;
}
#endif
#ifndef __HAVE_ARCH_PMDP_GET_AND_CLEAR
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static inline pmd_t pmdp_get_and_clear(struct mm_struct *mm,
unsigned long address,
pmd_t *pmdp)
{
pmd_t pmd = *pmdp;
pmd_clear(pmdp);
return pmd;
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
#endif
#ifndef __HAVE_ARCH_PMDP_GET_AND_CLEAR_FULL
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static inline pmd_t pmdp_get_and_clear_full(struct mm_struct *mm,
unsigned long address, pmd_t *pmdp,
int full)
{
return pmdp_get_and_clear(mm, address, pmdp);
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
#endif
#ifndef __HAVE_ARCH_PTEP_GET_AND_CLEAR_FULL
static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm,
unsigned long address, pte_t *ptep,
int full)
{
pte_t pte;
pte = ptep_get_and_clear(mm, address, ptep);
return pte;
}
#endif
/*
* Some architectures may be able to avoid expensive synchronization
* primitives when modifications are made to PTE's which are already
* not present, or in the process of an address space destruction.
*/
#ifndef __HAVE_ARCH_PTE_CLEAR_NOT_PRESENT_FULL
static inline void pte_clear_not_present_full(struct mm_struct *mm,
unsigned long address,
pte_t *ptep,
int full)
{
pte_clear(mm, address, ptep);
}
#endif
#ifndef __HAVE_ARCH_PTEP_CLEAR_FLUSH
extern pte_t ptep_clear_flush(struct vm_area_struct *vma,
unsigned long address,
pte_t *ptep);
#endif
#ifndef __HAVE_ARCH_PMDP_CLEAR_FLUSH
extern pmd_t pmdp_clear_flush(struct vm_area_struct *vma,
unsigned long address,
pmd_t *pmdp);
#endif
#ifndef __HAVE_ARCH_PTEP_SET_WRPROTECT
struct mm_struct;
static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long address, pte_t *ptep)
{
pte_t old_pte = *ptep;
set_pte_at(mm, address, ptep, pte_wrprotect(old_pte));
}
#endif
#ifndef __HAVE_ARCH_PMDP_SET_WRPROTECT
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static inline void pmdp_set_wrprotect(struct mm_struct *mm,
unsigned long address, pmd_t *pmdp)
{
pmd_t old_pmd = *pmdp;
set_pmd_at(mm, address, pmdp, pmd_wrprotect(old_pmd));
}
#else /* CONFIG_TRANSPARENT_HUGEPAGE */
static inline void pmdp_set_wrprotect(struct mm_struct *mm,
unsigned long address, pmd_t *pmdp)
{
BUG();
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
#endif
#ifndef __HAVE_ARCH_PMDP_SPLITTING_FLUSH
extern void pmdp_splitting_flush(struct vm_area_struct *vma,
unsigned long address, pmd_t *pmdp);
#endif
#ifndef __HAVE_ARCH_PGTABLE_DEPOSIT
extern void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
pgtable_t pgtable);
#endif
#ifndef __HAVE_ARCH_PGTABLE_WITHDRAW
extern pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp);
#endif
#ifndef __HAVE_ARCH_PMDP_INVALIDATE
extern void pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
pmd_t *pmdp);
#endif
#ifndef __HAVE_ARCH_PTE_SAME
static inline int pte_same(pte_t pte_a, pte_t pte_b)
{
return pte_val(pte_a) == pte_val(pte_b);
}
#endif
#ifndef __HAVE_ARCH_PTE_UNUSED
/*
* Some architectures provide facilities to virtualization guests
* so that they can flag allocated pages as unused. This allows the
* host to transparently reclaim unused pages. This function returns
* whether the pte's page is unused.
*/
static inline int pte_unused(pte_t pte)
{
return 0;
}
#endif
#ifndef __HAVE_ARCH_PMD_SAME
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static inline int pmd_same(pmd_t pmd_a, pmd_t pmd_b)
{
return pmd_val(pmd_a) == pmd_val(pmd_b);
}
#else /* CONFIG_TRANSPARENT_HUGEPAGE */
static inline int pmd_same(pmd_t pmd_a, pmd_t pmd_b)
{
BUG();
return 0;
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
#endif
#ifndef __HAVE_ARCH_PGD_OFFSET_GATE
#define pgd_offset_gate(mm, addr) pgd_offset(mm, addr)
#endif
#ifndef __HAVE_ARCH_MOVE_PTE
#define move_pte(pte, prot, old_addr, new_addr) (pte)
#endif
#ifndef pte_accessible
# define pte_accessible(mm, pte) ((void)(pte), 1)
#endif
#ifndef pte_present_nonuma
#define pte_present_nonuma(pte) pte_present(pte)
#endif
#ifndef flush_tlb_fix_spurious_fault
#define flush_tlb_fix_spurious_fault(vma, address) flush_tlb_page(vma, address)
#endif
#ifndef pgprot_noncached
#define pgprot_noncached(prot) (prot)
#endif
#ifndef pgprot_writecombine
#define pgprot_writecombine pgprot_noncached
#endif
#ifndef pgprot_device
#define pgprot_device pgprot_noncached
#endif
#ifndef pgprot_modify
#define pgprot_modify pgprot_modify
static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
{
if (pgprot_val(oldprot) == pgprot_val(pgprot_noncached(oldprot)))
newprot = pgprot_noncached(newprot);
if (pgprot_val(oldprot) == pgprot_val(pgprot_writecombine(oldprot)))
newprot = pgprot_writecombine(newprot);
if (pgprot_val(oldprot) == pgprot_val(pgprot_device(oldprot)))
newprot = pgprot_device(newprot);
return newprot;
}
#endif
/*
* When walking page tables, get the address of the next boundary,
* or the end address of the range if that comes earlier. Although no
* vma end wraps to 0, rounded up __boundary may wrap to 0 throughout.
*/
#define pgd_addr_end(addr, end) \
({ unsigned long __boundary = ((addr) + PGDIR_SIZE) & PGDIR_MASK; \
(__boundary - 1 < (end) - 1)? __boundary: (end); \
})
#ifndef pud_addr_end
#define pud_addr_end(addr, end) \
({ unsigned long __boundary = ((addr) + PUD_SIZE) & PUD_MASK; \
(__boundary - 1 < (end) - 1)? __boundary: (end); \
})
#endif
#ifndef pmd_addr_end
#define pmd_addr_end(addr, end) \
({ unsigned long __boundary = ((addr) + PMD_SIZE) & PMD_MASK; \
(__boundary - 1 < (end) - 1)? __boundary: (end); \
})
#endif
/*
* When walking page tables, we usually want to skip any p?d_none entries;
* and any p?d_bad entries - reporting the error before resetting to none.
* Do the tests inline, but report and clear the bad entry in mm/memory.c.
*/
void pgd_clear_bad(pgd_t *);
void pud_clear_bad(pud_t *);
void pmd_clear_bad(pmd_t *);
static inline int pgd_none_or_clear_bad(pgd_t *pgd)
{
if (pgd_none(*pgd))
return 1;
if (unlikely(pgd_bad(*pgd))) {
pgd_clear_bad(pgd);
return 1;
}
return 0;
}
static inline int pud_none_or_clear_bad(pud_t *pud)
{
if (pud_none(*pud))
return 1;
if (unlikely(pud_bad(*pud))) {
pud_clear_bad(pud);
return 1;
}
return 0;
}
static inline int pmd_none_or_clear_bad(pmd_t *pmd)
{
if (pmd_none(*pmd))
return 1;
if (unlikely(pmd_bad(*pmd))) {
pmd_clear_bad(pmd);
return 1;
}
return 0;
}
static inline pte_t __ptep_modify_prot_start(struct mm_struct *mm,
unsigned long addr,
pte_t *ptep)
{
/*
* Get the current pte state, but zero it out to make it
* non-present, preventing the hardware from asynchronously
* updating it.
*/
return ptep_get_and_clear(mm, addr, ptep);
}
static inline void __ptep_modify_prot_commit(struct mm_struct *mm,
unsigned long addr,
pte_t *ptep, pte_t pte)
{
/*
* The pte is non-present, so there's no hardware state to
* preserve.
*/
set_pte_at(mm, addr, ptep, pte);
}
#ifndef __HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION
/*
* Start a pte protection read-modify-write transaction, which
* protects against asynchronous hardware modifications to the pte.
* The intention is not to prevent the hardware from making pte
* updates, but to prevent any updates it may make from being lost.
*
* This does not protect against other software modifications of the
* pte; the appropriate pte lock must be held over the transation.
*
* Note that this interface is intended to be batchable, meaning that
* ptep_modify_prot_commit may not actually update the pte, but merely
* queue the update to be done at some later time. The update must be
* actually committed before the pte lock is released, however.
*/
static inline pte_t ptep_modify_prot_start(struct mm_struct *mm,
unsigned long addr,
pte_t *ptep)
{
return __ptep_modify_prot_start(mm, addr, ptep);
}
/*
* Commit an update to a pte, leaving any hardware-controlled bits in
* the PTE unmodified.
*/
static inline void ptep_modify_prot_commit(struct mm_struct *mm,
unsigned long addr,
pte_t *ptep, pte_t pte)
{
__ptep_modify_prot_commit(mm, addr, ptep, pte);
}
#endif /* __HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION */
#endif /* CONFIG_MMU */
/*
* A facility to provide lazy MMU batching. This allows PTE updates and
* page invalidations to be delayed until a call to leave lazy MMU mode
* is issued. Some architectures may benefit from doing this, and it is
* beneficial for both shadow and direct mode hypervisors, which may batch
* the PTE updates which happen during this window. Note that using this
* interface requires that read hazards be removed from the code. A read
* hazard could result in the direct mode hypervisor case, since the actual
* write to the page tables may not yet have taken place, so reads though
* a raw PTE pointer after it has been modified are not guaranteed to be
* up to date. This mode can only be entered and left under the protection of
* the page table locks for all page tables which may be modified. In the UP
* case, this is required so that preemption is disabled, and in the SMP case,
* it must synchronize the delayed page table writes properly on other CPUs.
*/
#ifndef __HAVE_ARCH_ENTER_LAZY_MMU_MODE
#define arch_enter_lazy_mmu_mode() do {} while (0)
#define arch_leave_lazy_mmu_mode() do {} while (0)
#define arch_flush_lazy_mmu_mode() do {} while (0)
#endif
/*
* A facility to provide batching of the reload of page tables and
* other process state with the actual context switch code for
* paravirtualized guests. By convention, only one of the batched
* update (lazy) modes (CPU, MMU) should be active at any given time,
* entry should never be nested, and entry and exits should always be
* paired. This is for sanity of maintaining and reasoning about the
* kernel code. In this case, the exit (end of the context switch) is
* in architecture-specific code, and so doesn't need a generic
* definition.
*/
#ifndef __HAVE_ARCH_START_CONTEXT_SWITCH
#define arch_start_context_switch(prev) do {} while (0)
#endif
#ifndef CONFIG_HAVE_ARCH_SOFT_DIRTY
static inline int pte_soft_dirty(pte_t pte)
{
return 0;
}
static inline int pmd_soft_dirty(pmd_t pmd)
{
return 0;
}
static inline pte_t pte_mksoft_dirty(pte_t pte)
{
return pte;
}
static inline pmd_t pmd_mksoft_dirty(pmd_t pmd)
{
return pmd;
}
static inline pte_t pte_swp_mksoft_dirty(pte_t pte)
{
return pte;
}
static inline int pte_swp_soft_dirty(pte_t pte)
{
return 0;
}
static inline pte_t pte_swp_clear_soft_dirty(pte_t pte)
{
return pte;
}
static inline pte_t pte_file_clear_soft_dirty(pte_t pte)
{
return pte;
}
static inline pte_t pte_file_mksoft_dirty(pte_t pte)
{
return pte;
}
static inline int pte_file_soft_dirty(pte_t pte)
{
return 0;
}
#endif
#ifndef __HAVE_PFNMAP_TRACKING
/*
* Interfaces that can be used by architecture code to keep track of
* memory type of pfn mappings specified by the remap_pfn_range,
* vm_insert_pfn.
*/
/*
* track_pfn_remap is called when a _new_ pfn mapping is being established
* by remap_pfn_range() for physical range indicated by pfn and size.
*/
static inline int track_pfn_remap(struct vm_area_struct *vma, pgprot_t *prot,
unsigned long pfn, unsigned long addr,
unsigned long size)
{
return 0;
}
/*
* track_pfn_insert is called when a _new_ single pfn is established
* by vm_insert_pfn().
*/
static inline int track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot,
unsigned long pfn)
{
return 0;
}
/*
* track_pfn_copy is called when vma that is covering the pfnmap gets
* copied through copy_page_range().
*/
static inline int track_pfn_copy(struct vm_area_struct *vma)
{
return 0;
}
/*
* untrack_pfn_vma is called while unmapping a pfnmap for a region.
* untrack can be called for a specific region indicated by pfn and size or
* can be for the entire vma (in which case pfn, size are zero).
*/
static inline void untrack_pfn(struct vm_area_struct *vma,
unsigned long pfn, unsigned long size)
{
}
#else
extern int track_pfn_remap(struct vm_area_struct *vma, pgprot_t *prot,
unsigned long pfn, unsigned long addr,
unsigned long size);
extern int track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot,
unsigned long pfn);
extern int track_pfn_copy(struct vm_area_struct *vma);
extern void untrack_pfn(struct vm_area_struct *vma, unsigned long pfn,
unsigned long size);
#endif
#ifdef __HAVE_COLOR_ZERO_PAGE
static inline int is_zero_pfn(unsigned long pfn)
{
extern unsigned long zero_pfn;
unsigned long offset_from_zero_pfn = pfn - zero_pfn;
return offset_from_zero_pfn <= (zero_page_mask >> PAGE_SHIFT);
}
#define my_zero_pfn(addr) page_to_pfn(ZERO_PAGE(addr))
#else
static inline int is_zero_pfn(unsigned long pfn)
{
extern unsigned long zero_pfn;
return pfn == zero_pfn;
}
static inline unsigned long my_zero_pfn(unsigned long addr)
{
extern unsigned long zero_pfn;
return zero_pfn;
}
#endif
#ifdef CONFIG_MMU
#ifndef CONFIG_TRANSPARENT_HUGEPAGE
static inline int pmd_trans_huge(pmd_t pmd)
{
return 0;
}
static inline int pmd_trans_splitting(pmd_t pmd)
{
return 0;
}
#ifndef __HAVE_ARCH_PMD_WRITE
static inline int pmd_write(pmd_t pmd)
{
BUG();
return 0;
}
#endif /* __HAVE_ARCH_PMD_WRITE */
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
#ifndef pmd_read_atomic
static inline pmd_t pmd_read_atomic(pmd_t *pmdp)
{
/*
* Depend on compiler for an atomic pmd read. NOTE: this is
* only going to work, if the pmdval_t isn't larger than
* an unsigned long.
*/
return *pmdp;
}
#endif
#ifndef pmd_move_must_withdraw
static inline int pmd_move_must_withdraw(spinlock_t *new_pmd_ptl,
spinlock_t *old_pmd_ptl)
{
/*
* With split pmd lock we also need to move preallocated
* PTE page table if new_pmd is on different PMD page table.
*/
return new_pmd_ptl != old_pmd_ptl;
}
#endif
/*
* This function is meant to be used by sites walking pagetables with
* the mmap_sem hold in read mode to protect against MADV_DONTNEED and
* transhuge page faults. MADV_DONTNEED can convert a transhuge pmd
* into a null pmd and the transhuge page fault can convert a null pmd
* into an hugepmd or into a regular pmd (if the hugepage allocation
* fails). While holding the mmap_sem in read mode the pmd becomes
* stable and stops changing under us only if it's not null and not a
* transhuge pmd. When those races occurs and this function makes a
* difference vs the standard pmd_none_or_clear_bad, the result is
* undefined so behaving like if the pmd was none is safe (because it
* can return none anyway). The compiler level barrier() is critically
* important to compute the two checks atomically on the same pmdval.
*
* For 32bit kernels with a 64bit large pmd_t this automatically takes
* care of reading the pmd atomically to avoid SMP race conditions
* against pmd_populate() when the mmap_sem is hold for reading by the
* caller (a special atomic read not done by "gcc" as in the generic
* version above, is also needed when THP is disabled because the page
* fault can populate the pmd from under us).
*/
static inline int pmd_none_or_trans_huge_or_clear_bad(pmd_t *pmd)
{
pmd_t pmdval = pmd_read_atomic(pmd);
/*
* The barrier will stabilize the pmdval in a register or on
* the stack so that it will stop changing under the code.
*
* When CONFIG_TRANSPARENT_HUGEPAGE=y on x86 32bit PAE,
* pmd_read_atomic is allowed to return a not atomic pmdval
* (for example pointing to an hugepage that has never been
* mapped in the pmd). The below checks will only care about
* the low part of the pmd with 32bit PAE x86 anyway, with the
* exception of pmd_none(). So the important thing is that if
* the low part of the pmd is found null, the high part will
* be also null or the pmd_none() check below would be
* confused.
*/
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
barrier();
#endif
if (pmd_none(pmdval) || pmd_trans_huge(pmdval))
return 1;
if (unlikely(pmd_bad(pmdval))) {
pmd_clear_bad(pmd);
return 1;
}
return 0;
}
/*
* This is a noop if Transparent Hugepage Support is not built into
* the kernel. Otherwise it is equivalent to
* pmd_none_or_trans_huge_or_clear_bad(), and shall only be called in
* places that already verified the pmd is not none and they want to
* walk ptes while holding the mmap sem in read mode (write mode don't
* need this). If THP is not enabled, the pmd can't go away under the
* code even if MADV_DONTNEED runs, but if THP is enabled we need to
* run a pmd_trans_unstable before walking the ptes after
* split_huge_page_pmd returns (because it may have run when the pmd
* become null, but then a page fault can map in a THP and not a
* regular page).
*/
static inline int pmd_trans_unstable(pmd_t *pmd)
{
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
return pmd_none_or_trans_huge_or_clear_bad(pmd);
#else
return 0;
#endif
}
#ifdef CONFIG_NUMA_BALANCING
/*
* _PAGE_NUMA distinguishes between an unmapped page table entry, an entry that
* is protected for PROT_NONE and a NUMA hinting fault entry. If the
* architecture defines __PAGE_PROTNONE then it should take that into account
* but those that do not can rely on the fact that the NUMA hinting scanner
* skips inaccessible VMAs.
*
* pte/pmd_present() returns true if pte/pmd_numa returns true. Page
* fault triggers on those regions if pte/pmd_numa returns true
* (because _PAGE_PRESENT is not set).
*/
#ifndef pte_numa
static inline int pte_numa(pte_t pte)
{
return ptenuma_flags(pte) == _PAGE_NUMA;
}
#endif
#ifndef pmd_numa
static inline int pmd_numa(pmd_t pmd)
{
return pmdnuma_flags(pmd) == _PAGE_NUMA;
}
#endif
/*
* pte/pmd_mknuma sets the _PAGE_ACCESSED bitflag automatically
* because they're called by the NUMA hinting minor page fault. If we
* wouldn't set the _PAGE_ACCESSED bitflag here, the TLB miss handler
* would be forced to set it later while filling the TLB after we
* return to userland. That would trigger a second write to memory
* that we optimize away by setting _PAGE_ACCESSED here.
*/
#ifndef pte_mknonnuma
static inline pte_t pte_mknonnuma(pte_t pte)
{
pteval_t val = pte_val(pte);
val &= ~_PAGE_NUMA;
val |= (_PAGE_PRESENT|_PAGE_ACCESSED);
return __pte(val);
}
#endif
#ifndef pmd_mknonnuma
static inline pmd_t pmd_mknonnuma(pmd_t pmd)
{
pmdval_t val = pmd_val(pmd);
val &= ~_PAGE_NUMA;
val |= (_PAGE_PRESENT|_PAGE_ACCESSED);
return __pmd(val);
}
#endif
#ifndef pte_mknuma
static inline pte_t pte_mknuma(pte_t pte)
{
pteval_t val = pte_val(pte);
VM_BUG_ON(!(val & _PAGE_PRESENT));
val &= ~_PAGE_PRESENT;
val |= _PAGE_NUMA;
return __pte(val);
}
#endif
#ifndef ptep_set_numa
static inline void ptep_set_numa(struct mm_struct *mm, unsigned long addr,
pte_t *ptep)
{
pte_t ptent = *ptep;
ptent = pte_mknuma(ptent);
set_pte_at(mm, addr, ptep, ptent);
return;
}
#endif
#ifndef pmd_mknuma
static inline pmd_t pmd_mknuma(pmd_t pmd)
{
pmdval_t val = pmd_val(pmd);
val &= ~_PAGE_PRESENT;
val |= _PAGE_NUMA;
return __pmd(val);
}
#endif
#ifndef pmdp_set_numa
static inline void pmdp_set_numa(struct mm_struct *mm, unsigned long addr,
pmd_t *pmdp)
{
pmd_t pmd = *pmdp;
pmd = pmd_mknuma(pmd);
set_pmd_at(mm, addr, pmdp, pmd);
return;
}
#endif
#else
static inline int pmd_numa(pmd_t pmd)
{
return 0;
}
static inline int pte_numa(pte_t pte)
{
return 0;
}
static inline pte_t pte_mknonnuma(pte_t pte)
{
return pte;
}
static inline pmd_t pmd_mknonnuma(pmd_t pmd)
{
return pmd;
}
static inline pte_t pte_mknuma(pte_t pte)
{
return pte;
}
static inline void ptep_set_numa(struct mm_struct *mm, unsigned long addr,
pte_t *ptep)
{
return;
}
static inline pmd_t pmd_mknuma(pmd_t pmd)
{
return pmd;
}
static inline void pmdp_set_numa(struct mm_struct *mm, unsigned long addr,
pmd_t *pmdp)
{
return ;
}
#endif /* CONFIG_NUMA_BALANCING */
#endif /* CONFIG_MMU */
#endif /* !__ASSEMBLY__ */
#ifndef io_remap_pfn_range
#define io_remap_pfn_range remap_pfn_range
#endif
#endif /* _ASM_GENERIC_PGTABLE_H */
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