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    Subject[PATCH v13 022/137] mm/filemap: Add __folio_lock_or_retry()
    Date
    Convert __lock_page_or_retry() to __folio_lock_or_retry().  This actually
    saves 4 bytes in the only caller of lock_page_or_retry() (due to better
    register allocation) and saves the 14 byte cost of calling page_folio()
    in __folio_lock_or_retry() for a total saving of 18 bytes. Also use
    a bool for the return type.

    Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
    Reviewed-by: Christoph Hellwig <hch@lst.de>
    Acked-by: Jeff Layton <jlayton@kernel.org>
    Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
    Reviewed-by: William Kucharski <william.kucharski@oracle.com>
    ---
    include/linux/pagemap.h | 11 +++++++----
    mm/filemap.c | 20 +++++++++-----------
    mm/memory.c | 8 ++++----
    3 files changed, 20 insertions(+), 19 deletions(-)

    diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
    index 7994b497d505..2e0a949a2b20 100644
    --- a/include/linux/pagemap.h
    +++ b/include/linux/pagemap.h
    @@ -655,7 +655,7 @@ static inline bool wake_page_match(struct wait_page_queue *wait_page,

    void __folio_lock(struct folio *folio);
    int __folio_lock_killable(struct folio *folio);
    -extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
    +bool __folio_lock_or_retry(struct folio *folio, struct mm_struct *mm,
    unsigned int flags);
    void unlock_page(struct page *page);
    void folio_unlock(struct folio *folio);
    @@ -716,13 +716,16 @@ static inline int lock_page_killable(struct page *page)
    * caller indicated that it can handle a retry.
    *
    * Return value and mmap_lock implications depend on flags; see
    - * __lock_page_or_retry().
    + * __folio_lock_or_retry().
    */
    -static inline int lock_page_or_retry(struct page *page, struct mm_struct *mm,
    +static inline bool lock_page_or_retry(struct page *page, struct mm_struct *mm,
    unsigned int flags)
    {
    + struct folio *folio;
    might_sleep();
    - return trylock_page(page) || __lock_page_or_retry(page, mm, flags);
    +
    + folio = page_folio(page);
    + return folio_trylock(folio) || __folio_lock_or_retry(folio, mm, flags);
    }

    /*
    diff --git a/mm/filemap.c b/mm/filemap.c
    index 018fad19146e..1dab6c126c7a 100644
    --- a/mm/filemap.c
    +++ b/mm/filemap.c
    @@ -1625,48 +1625,46 @@ static int __folio_lock_async(struct folio *folio, struct wait_page_queue *wait)

    /*
    * Return values:
    - * 1 - page is locked; mmap_lock is still held.
    - * 0 - page is not locked.
    + * true - folio is locked; mmap_lock is still held.
    + * false - folio is not locked.
    * mmap_lock has been released (mmap_read_unlock(), unless flags had both
    * FAULT_FLAG_ALLOW_RETRY and FAULT_FLAG_RETRY_NOWAIT set, in
    * which case mmap_lock is still held.
    *
    * If neither ALLOW_RETRY nor KILLABLE are set, will always return 1
    - * with the page locked and the mmap_lock unperturbed.
    + * with the folio locked and the mmap_lock unperturbed.
    */
    -int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
    +bool __folio_lock_or_retry(struct folio *folio, struct mm_struct *mm,
    unsigned int flags)
    {
    - struct folio *folio = page_folio(page);
    -
    if (fault_flag_allow_retry_first(flags)) {
    /*
    * CAUTION! In this case, mmap_lock is not released
    * even though return 0.
    */
    if (flags & FAULT_FLAG_RETRY_NOWAIT)
    - return 0;
    + return false;

    mmap_read_unlock(mm);
    if (flags & FAULT_FLAG_KILLABLE)
    folio_wait_locked_killable(folio);
    else
    folio_wait_locked(folio);
    - return 0;
    + return false;
    }
    if (flags & FAULT_FLAG_KILLABLE) {
    - int ret;
    + bool ret;

    ret = __folio_lock_killable(folio);
    if (ret) {
    mmap_read_unlock(mm);
    - return 0;
    + return false;
    }
    } else {
    __folio_lock(folio);
    }

    - return 1;
    + return true;
    }

    /**
    diff --git a/mm/memory.c b/mm/memory.c
    index 747a01d495f2..2f111f9b3dbc 100644
    --- a/mm/memory.c
    +++ b/mm/memory.c
    @@ -4248,7 +4248,7 @@ static vm_fault_t do_shared_fault(struct vm_fault *vmf)
    * We enter with non-exclusive mmap_lock (to exclude vma changes,
    * but allow concurrent faults).
    * The mmap_lock may have been released depending on flags and our
    - * return value. See filemap_fault() and __lock_page_or_retry().
    + * return value. See filemap_fault() and __folio_lock_or_retry().
    * If mmap_lock is released, vma may become invalid (for example
    * by other thread calling munmap()).
    */
    @@ -4489,7 +4489,7 @@ static vm_fault_t wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud)
    * concurrent faults).
    *
    * The mmap_lock may have been released depending on flags and our return value.
    - * See filemap_fault() and __lock_page_or_retry().
    + * See filemap_fault() and __folio_lock_or_retry().
    */
    static vm_fault_t handle_pte_fault(struct vm_fault *vmf)
    {
    @@ -4593,7 +4593,7 @@ static vm_fault_t handle_pte_fault(struct vm_fault *vmf)
    * By the time we get here, we already hold the mm semaphore
    *
    * The mmap_lock may have been released depending on flags and our
    - * return value. See filemap_fault() and __lock_page_or_retry().
    + * return value. See filemap_fault() and __folio_lock_or_retry().
    */
    static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
    unsigned long address, unsigned int flags)
    @@ -4749,7 +4749,7 @@ static inline void mm_account_fault(struct pt_regs *regs,
    * By the time we get here, we already hold the mm semaphore
    *
    * The mmap_lock may have been released depending on flags and our
    - * return value. See filemap_fault() and __lock_page_or_retry().
    + * return value. See filemap_fault() and __folio_lock_or_retry().
    */
    vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
    unsigned int flags, struct pt_regs *regs)
    --
    2.30.2
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