Commit 75edd345 authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
Browse files

tmpfs: preliminary minor tidyups 



Make a few cleanups in mm/shmem.c, before going on to complicate it.

shmem_alloc_page() will become more complicated: we can't afford to to
have that complication duplicated between a CONFIG_NUMA version and a
!CONFIG_NUMA version, so rearrange the #ifdef'ery there to yield a
single shmem_swapin() and a single shmem_alloc_page().

Yes, it's a shame to inflict the horrid pseudo-vma on non-NUMA
configurations, but eliminating it is a larger cleanup: I have an
alloc_pages_mpol() patchset not yet ready - mpol handling is subtle and
bug-prone, and changed yet again since my last version.

Move __SetPageLocked, __SetPageSwapBacked from shmem_getpage_gfp() to
shmem_alloc_page(): that SwapBacked flag will be useful in future, to
help to distinguish different cases appropriately.

And the SGP_DIRTY variant of SGP_CACHE is hard to understand and of
little use (IIRC it dates back to when shmem_getpage() returned the page
unlocked): kill it and do the necessary in shmem_file_read_iter().

But an arm64 build then complained that info may be uninitialized (where
shmem_getpage_gfp() deletes a freshly alloced page beyond eof), and
advancing to an "sgp <= SGP_CACHE" test jogged it back to reality.

Signed-off-by: default avatarHugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Yang Shi <yang.shi@linaro.org>
Cc: Ning Qu <quning@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent fa9949da

include/linux/mempolicy.h

+6 −0
Original line number Diff line number Diff line
@@ -228,6 +228,12 @@ static inline void mpol_free_shared_policy(struct shared_policy *p) 
{

}



static inline struct mempolicy *

mpol_shared_policy_lookup(struct shared_policy *sp, unsigned long idx)

{

	return NULL;

}



#define vma_policy(vma) NULL



static inline int

mm/shmem.c

+26 −43
Original line number Diff line number Diff line
@@ -101,7 +101,6 @@ struct shmem_falloc { 
enum sgp_type {

	SGP_READ,	/* don't exceed i_size, don't allocate page */

	SGP_CACHE,	/* don't exceed i_size, may allocate page */

	SGP_DIRTY,	/* like SGP_CACHE, but set new page dirty */

	SGP_WRITE,	/* may exceed i_size, may allocate !Uptodate page */

	SGP_FALLOC,	/* like SGP_WRITE, but make existing page Uptodate */

};
@@ -169,7 +168,7 @@ static inline int shmem_reacct_size(unsigned long flags, 


/*

 * ... whereas tmpfs objects are accounted incrementally as

 * pages are allocated, in order to allow huge sparse files.

 * pages are allocated, in order to allow large sparse files.

 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,

 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.

 */
@@ -947,8 +946,7 @@ redirty: 
	return 0;

}



#ifdef CONFIG_NUMA

#ifdef CONFIG_TMPFS

#if defined(CONFIG_NUMA) && defined(CONFIG_TMPFS)

static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)

{

	char buffer[64];
@@ -972,7 +970,18 @@ static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) 
	}

	return mpol;

}

#endif /* CONFIG_TMPFS */

#else /* !CONFIG_NUMA || !CONFIG_TMPFS */

static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)

{

}

static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)

{

	return NULL;

}

#endif /* CONFIG_NUMA && CONFIG_TMPFS */

#ifndef CONFIG_NUMA

#define vm_policy vm_private_data

#endif



static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,

			struct shmem_inode_info *info, pgoff_t index)
@@ -1008,39 +1017,17 @@ static struct page *shmem_alloc_page(gfp_t gfp, 
	pvma.vm_ops = NULL;

	pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index);



	page = alloc_page_vma(gfp, &pvma, 0);

	page = alloc_pages_vma(gfp, 0, &pvma, 0, numa_node_id(), false);

	if (page) {

		__SetPageLocked(page);

		__SetPageSwapBacked(page);

	}



	/* Drop reference taken by mpol_shared_policy_lookup() */

	mpol_cond_put(pvma.vm_policy);



	return page;

}

#else /* !CONFIG_NUMA */

#ifdef CONFIG_TMPFS

static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)

{

}

#endif /* CONFIG_TMPFS */



static inline struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,

			struct shmem_inode_info *info, pgoff_t index)

{

	return swapin_readahead(swap, gfp, NULL, 0);

}



static inline struct page *shmem_alloc_page(gfp_t gfp,

			struct shmem_inode_info *info, pgoff_t index)

{

	return alloc_page(gfp);

}

#endif /* CONFIG_NUMA */



#if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS)

static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)

{

	return NULL;

}

#endif



/*

 * When a page is moved from swapcache to shmem filecache (either by the
@@ -1084,8 +1071,6 @@ static int shmem_replace_page(struct page **pagep, gfp_t gfp, 
	copy_highpage(newpage, oldpage);

	flush_dcache_page(newpage);



	__SetPageLocked(newpage);

	__SetPageSwapBacked(newpage);

	SetPageUptodate(newpage);

	set_page_private(newpage, swap_index);

	SetPageSwapCache(newpage);
@@ -1155,7 +1140,7 @@ repeat: 
		page = NULL;

	}



	if (sgp != SGP_WRITE && sgp != SGP_FALLOC &&

	if (sgp <= SGP_CACHE &&

	    ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) {

		error = -EINVAL;

		goto unlock;
@@ -1275,9 +1260,6 @@ repeat: 
			error = -ENOMEM;

			goto decused;

		}



		__SetPageLocked(page);

		__SetPageSwapBacked(page);

		if (sgp == SGP_WRITE)

			__SetPageReferenced(page);
@@ -1321,12 +1303,10 @@ clear: 
			flush_dcache_page(page);

			SetPageUptodate(page);

		}

		if (sgp == SGP_DIRTY)

			set_page_dirty(page);

	}



	/* Perhaps the file has been truncated since we checked */

	if (sgp != SGP_WRITE && sgp != SGP_FALLOC &&

	if (sgp <= SGP_CACHE &&

	    ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) {

		if (alloced) {

			ClearPageDirty(page);
@@ -1633,7 +1613,7 @@ static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to) 
	 * and even mark them dirty, so it cannot exceed the max_blocks limit.

	 */

	if (!iter_is_iovec(to))

		sgp = SGP_DIRTY;

		sgp = SGP_CACHE;



	index = *ppos >> PAGE_SHIFT;

	offset = *ppos & ~PAGE_MASK;
@@ -1659,8 +1639,11 @@ static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to) 
				error = 0;

			break;

		}

		if (page)

		if (page) {

			if (sgp == SGP_CACHE)

				set_page_dirty(page);

			unlock_page(page);

		}



		/*

		 * We must evaluate after, since reads (unlike writes)

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