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consolidate generic_writepages and mpage_writepages

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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: Miklos Szeredi <mszeredi@suse.cz>
Acked-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Miklos Szeredi
2007-05-10 22:22:51 -07:00
committed by Linus Torvalds
parent e10cc1df1d
commit 0ea9718016
4 changed files with 92 additions and 150 deletions
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59
mm/page-writeback.c
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@@ -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
* @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()
* address_space_operation.
*
* If a page is already under I/O, generic_writepages() skips it, even
* If a page is already under I/O, write_cache_pages() skips it, even
* 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()
* 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
* WB_SYNC_ALL then we were called for data integrity and we must wait for
* existing IO to complete.
*
* Derived from mpage_writepages() - if you fix this you should check that
* also!
*/
int generic_writepages(struct address_space *mapping,
struct writeback_control *wbc)
int write_cache_pages(struct address_space *mapping,
struct writeback_control *wbc, writepage_t writepage,
void *data)
{
struct backing_dev_info *bdi = mapping->backing_dev_info;
int ret = 0;
int done = 0;
int (*writepage)(struct page *page, struct writeback_control *wbc);
struct pagevec pvec;
int nr_pages;
pgoff_t index;
@@ -625,12 +621,6 @@ int generic_writepages(struct address_space *mapping,
return 0;
}
writepage = mapping->a_ops->writepage;
/* deal with chardevs and other special file */
if (!writepage)
return 0;
pagevec_init(&pvec, 0);
if (wbc->range_cyclic) {
index = mapping->writeback_index; /* Start from prev offset */
@@ -682,8 +672,7 @@ retry:
continue;
}
ret = (*writepage)(page, wbc);
mapping_set_error(mapping, ret);
ret = (*writepage)(page, wbc, data);
if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE))
unlock_page(page);
@@ -710,6 +699,38 @@ retry:
mapping->writeback_index = index;
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);