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Date: Mon, 01 Sep 2014 17:02:04 +0900
From: Gioh Kim <gioh.kim@....com>
To: Jan Kara <jack@...e.cz>
CC: Alexander Viro <viro@...iv.linux.org.uk>,
Andrew Morton <akpm@...ux-foundation.org>,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
Peter Zijlstra <peterz@...radead.org>,
linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
Theodore Ts'o <tytso@....edu>,
Andreas Dilger <adilger.kernel@...ger.ca>,
linux-ext4@...r.kernel.org, Minchan Kim <minchan@...nel.org>,
Joonsoo Kim <js1304@...il.com>,
이건호 <gunho.lee@....com>
Subject: Re: [PATCHv3 1/3] fs/buffer.c: allocate buffer cache with user specific
flag
2014-09-01 오후 4:53, Jan Kara 쓴 글:
> On Fri 29-08-14 13:48:27, Gioh Kim wrote:
>> What about below?: add gfp for __getblk_slow, change __getblk into __getblk_gfp,
>> getblk_unmovable and __getblk are, I think, symmetric.
>>
>> If you say OK, I'm going to send v4 with tabs ;-)
> Yes, this looks like what I wanted. I've just spotted two typos in
> comments and one function which should be inline (see below). Thanks for
> work!
>
> Honza
Thank you too!
I'm going to report the next spin soon.
>
>> diff --git a/fs/buffer.c b/fs/buffer.c
>> index 8f05111..21711c78 100644
>> --- a/fs/buffer.c
>> +++ b/fs/buffer.c
>> @@ -993,7 +993,7 @@ init_page_buffers(struct page *page, struct block_device *bdev,
>> */
>> static int
>> grow_dev_page(struct block_device *bdev, sector_t block,
>> - pgoff_t index, int size, int sizebits)
>> + pgoff_t index, int size, int sizebits, gfp_t gfp)
>> {
>> struct inode *inode = bdev->bd_inode;
>> struct page *page;
>> @@ -1002,10 +1002,10 @@ grow_dev_page(struct block_device *bdev, sector_t block,
>> int ret = 0; /* Will call free_more_memory() */
>> gfp_t gfp_mask;
>>
>> - gfp_mask = mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS;
>> - gfp_mask |= __GFP_MOVABLE;
>> + gfp_mask = (mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS) | gfp;
>> +
>> /*
>> - * XXX: __getblk_slow() can not really deal with failure and
>> + * XXX: __getblk_gfp() can not really deal with failure and
> You can leave __getblk_slow() here I believe.
I got it. It's my mistake.
>
>
>> * will endlessly loop on improvised global reclaim. Prefer
>> * looping in the allocator rather than here, at least that
>> * code knows what it's doing.
>> @@ -1058,7 +1058,7 @@ failed:
>> * that page was dirty, the buffers are set dirty also.
>> */
>> static int
>> -grow_buffers(struct block_device *bdev, sector_t block, int size)
>> +grow_buffers(struct block_device *bdev, sector_t block, int size, gfp_t gfp)
>> {
>> pgoff_t index;
>> int sizebits;
>> @@ -1085,11 +1085,12 @@ grow_buffers(struct block_device *bdev, sector_t block, int size)
>> }
>>
>> /* Create a page with the proper size buffers.. */
>> - return grow_dev_page(bdev, block, index, size, sizebits);
>> + return grow_dev_page(bdev, block, index, size, sizebits, gfp);
>> }
>>
>> -static struct buffer_head *
>> -__getblk_slow(struct block_device *bdev, sector_t block, int size)
>> +struct buffer_head *
>> +__getblk_slow(struct block_device *bdev, sector_t block,
>> + unsigned size, gfp_t gfp)
>> {
>> /* Size must be multiple of hard sectorsize */
>> if (unlikely(size & (bdev_logical_block_size(bdev)-1) ||
>> @@ -1111,13 +1112,14 @@ __getblk_slow(struct block_device *bdev, sector_t block, int size)
>> if (bh)
>> return bh;
>>
>> - ret = grow_buffers(bdev, block, size);
>> + ret = grow_buffers(bdev, block, size, gfp);
>> if (ret < 0)
>> return NULL;
>> if (ret == 0)
>> free_more_memory();
>> }
>> }
>> +EXPORT_SYMBOL(__getblk_slow);
>>
>> /*
>> * The relationship between dirty buffers and dirty pages:
>> @@ -1371,24 +1373,25 @@ __find_get_block(struct block_device *bdev, sector_t block, unsigned size)
>> EXPORT_SYMBOL(__find_get_block);
>>
>> /*
>> - * __getblk will locate (and, if necessary, create) the buffer_head
>> + * __getblk_gfp will locate (and, if necessary, create) the buffer_head
>> * which corresponds to the passed block_device, block and size. The
>> * returned buffer has its reference count incremented.
>> *
>> - * __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers()
>> - * attempt is failing. FIXME, perhaps?
>> + * __getblk()_gfp will lock up the machine if grow_dev_page's
> _gfp should be before () in the line above.
I got it.
>
>> + * try_to_free_buffers() attempt is failing. FIXME, perhaps?
>> */
>> struct buffer_head *
>> -__getblk(struct block_device *bdev, sector_t block, unsigned size)
>> +__getblk_gfp(struct block_device *bdev, sector_t block,
>> + unsigned size, gfp_t gfp)
>> {
>> struct buffer_head *bh = __find_get_block(bdev, block, size);
>>
>> might_sleep();
>> if (bh == NULL)
>> - bh = __getblk_slow(bdev, block, size);
>> + bh = __getblk_slow(bdev, block, size, gfp);
>> return bh;
>> }
>> -EXPORT_SYMBOL(__getblk);
>> +EXPORT_SYMBOL(__getblk_gfp);
>>
>> /*
>> * Do async read-ahead on a buffer..
>> @@ -1410,18 +1413,39 @@ EXPORT_SYMBOL(__breadahead);
>> * @size: size (in bytes) to read
>> *
>> * Reads a specified block, and returns buffer head that contains it.
>> + * The page cache is allocated from movable area so that it can be migrated.
>> * It returns NULL if the block was unreadable.
>> */
>> struct buffer_head *
>> __bread(struct block_device *bdev, sector_t block, unsigned size)
>> {
>> - struct buffer_head *bh = __getblk(bdev, block, size);
>> + return __bread_gfp(bdev, block, size, __GFP_MOVABLE);
>> +}
>> +EXPORT_SYMBOL(__bread);
> This can be just inline defined in buffer_head.h.
I got it.
>
>
>> +
>> +/**
>> + * __bread_gfp() - reads a specified block and returns the bh
>> + * @bdev: the block_device to read from
>> + * @block: number of block
>> + * @size: size (in bytes) to read
>> + * @gfp: page allocation flag
>> + *
>> + * Reads a specified block, and returns buffer head that contains it.
>> + * The page cache can be allocated from non-movable area
>> + * not to prevent page migration if you set gfp to zero.
>> + * It returns NULL if the block was unreadable.
>> + */
>> +struct buffer_head *
>> +__bread_gfp(struct block_device *bdev, sector_t block,
>> + unsigned size, gfp_t gfp)
>> +{
>> + struct buffer_head *bh = __getblk_gfp(bdev, block, size, gfp);
>>
>> if (likely(bh) && !buffer_uptodate(bh))
>> bh = __bread_slow(bh);
>> return bh;
>> }
>> -EXPORT_SYMBOL(__bread);
>> +EXPORT_SYMBOL(__bread_gfp);
>>
>> /*
>> * invalidate_bh_lrus() is called rarely - but not only at unmount.
>> diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
>> index 324329c..6073f5d 100644
>> --- a/include/linux/buffer_head.h
>> +++ b/include/linux/buffer_head.h
>> @@ -175,12 +175,14 @@ void __wait_on_buffer(struct buffer_head *);
>> wait_queue_head_t *bh_waitq_head(struct buffer_head *bh);
>> struct buffer_head *__find_get_block(struct block_device *bdev, sector_t block,
>> unsigned size);
>> -struct buffer_head *__getblk(struct block_device *bdev, sector_t block,
>> - unsigned size);
>> +struct buffer_head *__getblk_gfp(struct block_device *bdev, sector_t block,
>> + unsigned size, gfp_t gfp);
>> void __brelse(struct buffer_head *);
>> void __bforget(struct buffer_head *);
>> void __breadahead(struct block_device *, sector_t block, unsigned int size);
>> struct buffer_head *__bread(struct block_device *, sector_t block, unsigned size);
>> +struct buffer_head *__bread_gfp(struct block_device *,
>> + sector_t block, unsigned size, gfp_t gfp);
>> void invalidate_bh_lrus(void);
>> struct buffer_head *alloc_buffer_head(gfp_t gfp_flags);
>> void free_buffer_head(struct buffer_head * bh);
>> @@ -295,7 +297,13 @@ static inline void bforget(struct buffer_head *bh)
>> static inline struct buffer_head *
>> sb_bread(struct super_block *sb, sector_t block)
>> {
>> - return __bread(sb->s_bdev, block, sb->s_blocksize);
>> + return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE);
>> +}
>> +
>> +static inline struct buffer_head *
>> +sb_bread_unmovable(struct super_block *sb, sector_t block)
>> +{
>> + return __bread_gfp(sb->s_bdev, block, sb->s_blocksize, 0);
>> }
>>
>> static inline void
>> @@ -307,7 +315,7 @@ sb_breadahead(struct super_block *sb, sector_t block)
>> static inline struct buffer_head *
>> sb_getblk(struct super_block *sb, sector_t block)
>> {
>> - return __getblk(sb->s_bdev, block, sb->s_blocksize);
>> + return __getblk_gfp(sb->s_bdev, block, sb->s_blocksize, __GFP_MOVABLE);
>> }
>>
>> static inline struct buffer_head *
>> @@ -344,6 +352,20 @@ static inline void lock_buffer(struct buffer_head *bh)
>> __lock_buffer(bh);
>> }
>>
>> +static inline struct buffer_head *getblk_unmovable(struct block_device *bdev,
>> + sector_t block,
>> + unsigned size)
>> +{
>> + return __getblk_gfp(bdev, block, size, 0);
>> +}
>> +
>> +static inline struct buffer_head *__getblk(struct block_device *bdev,
>> + sector_t block,
>> + unsigned size)
>> +{
>> + return __getblk_gfp(bdev, block, size, __GFP_MOVABLE);
>> +}
>> +
>> extern int __set_page_dirty_buffers(struct page *page);
>>
>> #else /* CONFIG_BLOCK */
>> --
>> 1.7.9.5
>>
--
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