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Date: Thu, 31 Mar 2022 12:08:20 +0530 From: Charan Teja Kalla <quic_charante@...cinc.com> To: <akpm@...ux-foundation.org>, <willy@...radead.org>, <markhemm@...glemail.com>, <hughd@...gle.com>, <rientjes@...gle.com>, <surenb@...gle.com>, <shakeelb@...gle.com> CC: <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>, Charan Teja Reddy <quic_charante@...cinc.com> Subject: [PATCH RESEND V5,1/2] mm: fadvise: move 'endbyte' calculations to helper function From: Charan Teja Reddy <quic_charante@...cinc.com> Move the 'endbyte' calculations that determines last byte that fadvise can to a helper function. This is a preparatory change made for shmem_fadvise() functionality in the next patch. No functional changes in this patch. Signed-off-by: Charan Teja Reddy <quic_charante@...cinc.com> --- Changes in V5: -- Moved the 'endbyte' calculation to a helper function. -- This patch is newly raised in V5 thus no change exists from v1 to v4. mm/fadvise.c | 11 +---------- mm/internal.h | 21 +++++++++++++++++++++ 2 files changed, 22 insertions(+), 10 deletions(-) diff --git a/mm/fadvise.c b/mm/fadvise.c index 338f160..0c82be2 100644 --- a/mm/fadvise.c +++ b/mm/fadvise.c @@ -65,16 +65,7 @@ int generic_fadvise(struct file *file, loff_t offset, loff_t len, int advice) return 0; } - /* - * Careful about overflows. Len == 0 means "as much as possible". Use - * unsigned math because signed overflows are undefined and UBSan - * complains. - */ - endbyte = (u64)offset + (u64)len; - if (!len || endbyte < len) - endbyte = -1; - else - endbyte--; /* inclusive */ + endbyte = fadvise_calc_endbyte(offset, len); switch (advice) { case POSIX_FADV_NORMAL: diff --git a/mm/internal.h b/mm/internal.h index 58dc6ad..b02f07e 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -546,6 +546,27 @@ static inline void vunmap_range_noflush(unsigned long start, unsigned long end) #endif /* !CONFIG_MMU */ /* + * Helper function to get the endbyte of a file that fadvise can operate on. + */ +static inline loff_t fadvise_calc_endbyte(loff_t offset, loff_t len) +{ + loff_t endbyte; + + /* + * Careful about overflows. Len == 0 means "as much as possible". Use + * unsigned math because signed overflows are undefined and UBSan + * complains. + */ + endbyte = (u64)offset + (u64)len; + if (!len || endbyte < len) + endbyte = -1; + else + endbyte--; /* inclusive */ + + return endbyte; +} + +/* * Return the mem_map entry representing the 'offset' subpage within * the maximally aligned gigantic page 'base'. Handle any discontiguity * in the mem_map at MAX_ORDER_NR_PAGES boundaries. -- 2.7.4
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