Commit 0ea97180 authored by Miklos Szeredi's avatar Miklos Szeredi Committed by Linus Torvalds

consolidate generic_writepages and mpage_writepages

Clean up massive code duplication between mpage_writepages() and
generic_writepages().

The new generic function, write_cache_pages() takes a function pointer
argument, which will be called for each page to be written.

Maybe cifs_writepages() too can use this infrastructure, but I'm not
touching that with a ten-foot pole.

The upcoming page writeback support in fuse will also want this.
Signed-off-by: default avatarMiklos Szeredi <mszeredi@suse.cz>
Acked-by: default avatarChristoph Hellwig <hch@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e10cc1df
...@@ -454,11 +454,18 @@ EXPORT_SYMBOL(mpage_readpage); ...@@ -454,11 +454,18 @@ EXPORT_SYMBOL(mpage_readpage);
* written, so it can intelligently allocate a suitably-sized BIO. For now, * written, so it can intelligently allocate a suitably-sized BIO. For now,
* just allocate full-size (16-page) BIOs. * just allocate full-size (16-page) BIOs.
*/ */
static struct bio * struct mpage_data {
__mpage_writepage(struct bio *bio, struct page *page, get_block_t get_block, struct bio *bio;
sector_t *last_block_in_bio, int *ret, struct writeback_control *wbc, sector_t last_block_in_bio;
writepage_t writepage_fn) get_block_t *get_block;
unsigned use_writepage;
};
static int __mpage_writepage(struct page *page, struct writeback_control *wbc,
void *data)
{ {
struct mpage_data *mpd = data;
struct bio *bio = mpd->bio;
struct address_space *mapping = page->mapping; struct address_space *mapping = page->mapping;
struct inode *inode = page->mapping->host; struct inode *inode = page->mapping->host;
const unsigned blkbits = inode->i_blkbits; const unsigned blkbits = inode->i_blkbits;
...@@ -476,6 +483,7 @@ __mpage_writepage(struct bio *bio, struct page *page, get_block_t get_block, ...@@ -476,6 +483,7 @@ __mpage_writepage(struct bio *bio, struct page *page, get_block_t get_block,
int length; int length;
struct buffer_head map_bh; struct buffer_head map_bh;
loff_t i_size = i_size_read(inode); loff_t i_size = i_size_read(inode);
int ret = 0;
if (page_has_buffers(page)) { if (page_has_buffers(page)) {
struct buffer_head *head = page_buffers(page); struct buffer_head *head = page_buffers(page);
...@@ -538,7 +546,7 @@ __mpage_writepage(struct bio *bio, struct page *page, get_block_t get_block, ...@@ -538,7 +546,7 @@ __mpage_writepage(struct bio *bio, struct page *page, get_block_t get_block,
map_bh.b_state = 0; map_bh.b_state = 0;
map_bh.b_size = 1 << blkbits; map_bh.b_size = 1 << blkbits;
if (get_block(inode, block_in_file, &map_bh, 1)) if (mpd->get_block(inode, block_in_file, &map_bh, 1))
goto confused; goto confused;
if (buffer_new(&map_bh)) if (buffer_new(&map_bh))
unmap_underlying_metadata(map_bh.b_bdev, unmap_underlying_metadata(map_bh.b_bdev,
...@@ -584,7 +592,7 @@ __mpage_writepage(struct bio *bio, struct page *page, get_block_t get_block, ...@@ -584,7 +592,7 @@ __mpage_writepage(struct bio *bio, struct page *page, get_block_t get_block,
/* /*
* This page will go to BIO. Do we need to send this BIO off first? * This page will go to BIO. Do we need to send this BIO off first?
*/ */
if (bio && *last_block_in_bio != blocks[0] - 1) if (bio && mpd->last_block_in_bio != blocks[0] - 1)
bio = mpage_bio_submit(WRITE, bio); bio = mpage_bio_submit(WRITE, bio);
alloc_new: alloc_new:
...@@ -641,7 +649,7 @@ __mpage_writepage(struct bio *bio, struct page *page, get_block_t get_block, ...@@ -641,7 +649,7 @@ __mpage_writepage(struct bio *bio, struct page *page, get_block_t get_block,
boundary_block, 1 << blkbits); boundary_block, 1 << blkbits);
} }
} else { } else {
*last_block_in_bio = blocks[blocks_per_page - 1]; mpd->last_block_in_bio = blocks[blocks_per_page - 1];
} }
goto out; goto out;
...@@ -649,18 +657,19 @@ __mpage_writepage(struct bio *bio, struct page *page, get_block_t get_block, ...@@ -649,18 +657,19 @@ __mpage_writepage(struct bio *bio, struct page *page, get_block_t get_block,
if (bio) if (bio)
bio = mpage_bio_submit(WRITE, bio); bio = mpage_bio_submit(WRITE, bio);
if (writepage_fn) { if (mpd->use_writepage) {
*ret = (*writepage_fn)(page, wbc); ret = mapping->a_ops->writepage(page, wbc);
} else { } else {
*ret = -EAGAIN; ret = -EAGAIN;
goto out; goto out;
} }
/* /*
* The caller has a ref on the inode, so *mapping is stable * The caller has a ref on the inode, so *mapping is stable
*/ */
mapping_set_error(mapping, *ret); mapping_set_error(mapping, ret);
out: out:
return bio; mpd->bio = bio;
return ret;
} }
/** /**
...@@ -683,120 +692,27 @@ __mpage_writepage(struct bio *bio, struct page *page, get_block_t get_block, ...@@ -683,120 +692,27 @@ __mpage_writepage(struct bio *bio, struct page *page, get_block_t get_block,
* the call was made get new I/O started against them. If wbc->sync_mode is * the call was made get new I/O started against them. If wbc->sync_mode is
* WB_SYNC_ALL then we were called for data integrity and we must wait for * WB_SYNC_ALL then we were called for data integrity and we must wait for
* existing IO to complete. * existing IO to complete.
*
* If you fix this you should check generic_writepages() also!
*/ */
int int
mpage_writepages(struct address_space *mapping, mpage_writepages(struct address_space *mapping,
struct writeback_control *wbc, get_block_t get_block) struct writeback_control *wbc, get_block_t get_block)
{ {
struct backing_dev_info *bdi = mapping->backing_dev_info; int ret;
struct bio *bio = NULL;
sector_t last_block_in_bio = 0; if (!get_block)
int ret = 0; ret = generic_writepages(mapping, wbc);
int done = 0; else {
int (*writepage)(struct page *page, struct writeback_control *wbc); struct mpage_data mpd = {
struct pagevec pvec; .bio = NULL,
int nr_pages; .last_block_in_bio = 0,
pgoff_t index; .get_block = get_block,
pgoff_t end; /* Inclusive */ .use_writepage = 1,
int scanned = 0; };
int range_whole = 0;
ret = write_cache_pages(mapping, wbc, __mpage_writepage, &mpd);
if (wbc->nonblocking && bdi_write_congested(bdi)) { if (mpd.bio)
wbc->encountered_congestion = 1; mpage_bio_submit(WRITE, mpd.bio);
return 0;
}
writepage = NULL;
if (get_block == NULL)
writepage = mapping->a_ops->writepage;
pagevec_init(&pvec, 0);
if (wbc->range_cyclic) {
index = mapping->writeback_index; /* Start from prev offset */
end = -1;
} else {
index = wbc->range_start >> PAGE_CACHE_SHIFT;
end = wbc->range_end >> PAGE_CACHE_SHIFT;
if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
range_whole = 1;
scanned = 1;
} }
retry:
while (!done && (index <= end) &&
(nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
PAGECACHE_TAG_DIRTY,
min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
unsigned i;
scanned = 1;
for (i = 0; i < nr_pages; i++) {
struct page *page = pvec.pages[i];
/*
* At this point we hold neither mapping->tree_lock nor
* lock on the page itself: the page may be truncated or
* invalidated (changing page->mapping to NULL), or even
* swizzled back from swapper_space to tmpfs file
* mapping
*/
lock_page(page);
if (unlikely(page->mapping != mapping)) {
unlock_page(page);
continue;
}
if (!wbc->range_cyclic && page->index > end) {
done = 1;
unlock_page(page);
continue;
}
if (wbc->sync_mode != WB_SYNC_NONE)
wait_on_page_writeback(page);
if (PageWriteback(page) ||
!clear_page_dirty_for_io(page)) {
unlock_page(page);
continue;
}
if (writepage) {
ret = (*writepage)(page, wbc);
mapping_set_error(mapping, ret);
} else {
bio = __mpage_writepage(bio, page, get_block,
&last_block_in_bio, &ret, wbc,
page->mapping->a_ops->writepage);
}
if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE))
unlock_page(page);
if (ret || (--(wbc->nr_to_write) <= 0))
done = 1;
if (wbc->nonblocking && bdi_write_congested(bdi)) {
wbc->encountered_congestion = 1;
done = 1;
}
}
pagevec_release(&pvec);
cond_resched();
}
if (!scanned && !done) {
/*
* We hit the last page and there is more work to be done: wrap
* back to the start of the file
*/
scanned = 1;
index = 0;
goto retry;
}
if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
mapping->writeback_index = index;
if (bio)
mpage_bio_submit(WRITE, bio);
return ret; return ret;
} }
EXPORT_SYMBOL(mpage_writepages); EXPORT_SYMBOL(mpage_writepages);
...@@ -804,15 +720,15 @@ EXPORT_SYMBOL(mpage_writepages); ...@@ -804,15 +720,15 @@ EXPORT_SYMBOL(mpage_writepages);
int mpage_writepage(struct page *page, get_block_t get_block, int mpage_writepage(struct page *page, get_block_t get_block,
struct writeback_control *wbc) struct writeback_control *wbc)
{ {
int ret = 0; struct mpage_data mpd = {
struct bio *bio; .bio = NULL,
sector_t last_block_in_bio = 0; .last_block_in_bio = 0,
.get_block = get_block,
bio = __mpage_writepage(NULL, page, get_block, .use_writepage = 0,
&last_block_in_bio, &ret, wbc, NULL); };
if (bio) int ret = __mpage_writepage(page, wbc, &mpd);
mpage_bio_submit(WRITE, bio); if (mpd.bio)
mpage_bio_submit(WRITE, mpd.bio);
return ret; return ret;
} }
EXPORT_SYMBOL(mpage_writepage); EXPORT_SYMBOL(mpage_writepage);
...@@ -12,7 +12,6 @@ ...@@ -12,7 +12,6 @@
#ifdef CONFIG_BLOCK #ifdef CONFIG_BLOCK
struct writeback_control; struct writeback_control;
typedef int (writepage_t)(struct page *page, struct writeback_control *wbc);
int mpage_readpages(struct address_space *mapping, struct list_head *pages, int mpage_readpages(struct address_space *mapping, struct list_head *pages,
unsigned nr_pages, get_block_t get_block); unsigned nr_pages, get_block_t get_block);
......
...@@ -111,9 +111,15 @@ balance_dirty_pages_ratelimited(struct address_space *mapping) ...@@ -111,9 +111,15 @@ balance_dirty_pages_ratelimited(struct address_space *mapping)
balance_dirty_pages_ratelimited_nr(mapping, 1); balance_dirty_pages_ratelimited_nr(mapping, 1);
} }
typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
void *data);
int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0); int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0);
extern int generic_writepages(struct address_space *mapping, int generic_writepages(struct address_space *mapping,
struct writeback_control *wbc); struct writeback_control *wbc);
int write_cache_pages(struct address_space *mapping,
struct writeback_control *wbc, writepage_t writepage,
void *data);
int do_writepages(struct address_space *mapping, struct writeback_control *wbc); int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
int sync_page_range(struct inode *inode, struct address_space *mapping, int sync_page_range(struct inode *inode, struct address_space *mapping,
loff_t pos, loff_t count); loff_t pos, loff_t count);
......
...@@ -588,31 +588,27 @@ void __init page_writeback_init(void) ...@@ -588,31 +588,27 @@ void __init page_writeback_init(void)
} }
/** /**
* generic_writepages - walk the list of dirty pages of the given address space and writepage() all of them. * write_cache_pages - walk the list of dirty pages of the given address space and write all of them.
* @mapping: address space structure to write * @mapping: address space structure to write
* @wbc: subtract the number of written pages from *@wbc->nr_to_write * @wbc: subtract the number of written pages from *@wbc->nr_to_write
* @writepage: function called for each page
* @data: data passed to writepage function
* *
* This is a library function, which implements the writepages() * If a page is already under I/O, write_cache_pages() skips it, even
* address_space_operation.
*
* If a page is already under I/O, generic_writepages() skips it, even
* if it's dirty. This is desirable behaviour for memory-cleaning writeback, * if it's dirty. This is desirable behaviour for memory-cleaning writeback,
* but it is INCORRECT for data-integrity system calls such as fsync(). fsync() * but it is INCORRECT for data-integrity system calls such as fsync(). fsync()
* and msync() need to guarantee that all the data which was dirty at the time * and msync() need to guarantee that all the data which was dirty at the time
* the call was made get new I/O started against them. If wbc->sync_mode is * the call was made get new I/O started against them. If wbc->sync_mode is
* WB_SYNC_ALL then we were called for data integrity and we must wait for * WB_SYNC_ALL then we were called for data integrity and we must wait for
* existing IO to complete. * existing IO to complete.
*
* Derived from mpage_writepages() - if you fix this you should check that
* also!
*/ */
int generic_writepages(struct address_space *mapping, int write_cache_pages(struct address_space *mapping,
struct writeback_control *wbc) struct writeback_control *wbc, writepage_t writepage,
void *data)
{ {
struct backing_dev_info *bdi = mapping->backing_dev_info; struct backing_dev_info *bdi = mapping->backing_dev_info;
int ret = 0; int ret = 0;
int done = 0; int done = 0;
int (*writepage)(struct page *page, struct writeback_control *wbc);
struct pagevec pvec; struct pagevec pvec;
int nr_pages; int nr_pages;
pgoff_t index; pgoff_t index;
...@@ -625,12 +621,6 @@ int generic_writepages(struct address_space *mapping, ...@@ -625,12 +621,6 @@ int generic_writepages(struct address_space *mapping,
return 0; return 0;
} }
writepage = mapping->a_ops->writepage;
/* deal with chardevs and other special file */
if (!writepage)
return 0;
pagevec_init(&pvec, 0); pagevec_init(&pvec, 0);
if (wbc->range_cyclic) { if (wbc->range_cyclic) {
index = mapping->writeback_index; /* Start from prev offset */ index = mapping->writeback_index; /* Start from prev offset */
...@@ -682,8 +672,7 @@ int generic_writepages(struct address_space *mapping, ...@@ -682,8 +672,7 @@ int generic_writepages(struct address_space *mapping,
continue; continue;
} }
ret = (*writepage)(page, wbc); ret = (*writepage)(page, wbc, data);
mapping_set_error(mapping, ret);
if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE)) if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE))
unlock_page(page); unlock_page(page);
...@@ -710,6 +699,38 @@ int generic_writepages(struct address_space *mapping, ...@@ -710,6 +699,38 @@ int generic_writepages(struct address_space *mapping,
mapping->writeback_index = index; mapping->writeback_index = index;
return ret; return ret;
} }
EXPORT_SYMBOL(write_cache_pages);
/*
* Function used by generic_writepages to call the real writepage
* function and set the mapping flags on error
*/
static int __writepage(struct page *page, struct writeback_control *wbc,
void *data)
{
struct address_space *mapping = data;
int ret = mapping->a_ops->writepage(page, wbc);
mapping_set_error(mapping, ret);
return ret;
}
/**
* generic_writepages - walk the list of dirty pages of the given address space and writepage() all of them.
* @mapping: address space structure to write
* @wbc: subtract the number of written pages from *@wbc->nr_to_write
*
* This is a library function, which implements the writepages()
* address_space_operation.
*/
int generic_writepages(struct address_space *mapping,
struct writeback_control *wbc)
{
/* deal with chardevs and other special file */
if (!mapping->a_ops->writepage)
return 0;
return write_cache_pages(mapping, wbc, __writepage, mapping);
}
EXPORT_SYMBOL(generic_writepages); EXPORT_SYMBOL(generic_writepages);
......
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