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fs: move page_cache_seek_hole_data to iomap.c

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This function is only used by the iomap code, depends on being called
from it, and will soon stop poking into buffer head internals.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
This commit is contained in:
Christoph Hellwig 2018-06-01 09:04:40 -07:00 committed by Darrick J. Wong
parent b84e772299
commit 8a78cb1f1b
3 changed files with 116 additions and 116 deletions
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114
fs/buffer.c
View File

@ -3427,120 +3427,6 @@ int bh_submit_read(struct buffer_head *bh)
}
EXPORT_SYMBOL(bh_submit_read);
/*
* Seek for SEEK_DATA / SEEK_HOLE within @page, starting at @lastoff.
*
* Returns the offset within the file on success, and -ENOENT otherwise.
*/
static loff_t
page_seek_hole_data(struct page *page, loff_t lastoff, int whence)
{
loff_t offset = page_offset(page);
struct buffer_head *bh, *head;
bool seek_data = whence == SEEK_DATA;
if (lastoff < offset)
lastoff = offset;
bh = head = page_buffers(page);
do {
offset += bh->b_size;
if (lastoff >= offset)
continue;
/*
* Unwritten extents that have data in the page cache covering
* them can be identified by the BH_Unwritten state flag.
* Pages with multiple buffers might have a mix of holes, data
* and unwritten extents - any buffer with valid data in it
* should have BH_Uptodate flag set on it.
*/
if ((buffer_unwritten(bh) || buffer_uptodate(bh)) == seek_data)
return lastoff;
lastoff = offset;
} while ((bh = bh->b_this_page) != head);
return -ENOENT;
}
/*
* Seek for SEEK_DATA / SEEK_HOLE in the page cache.
*
* Within unwritten extents, the page cache determines which parts are holes
* and which are data: unwritten and uptodate buffer heads count as data;
* everything else counts as a hole.
*
* Returns the resulting offset on successs, and -ENOENT otherwise.
*/
loff_t
page_cache_seek_hole_data(struct inode *inode, loff_t offset, loff_t length,
int whence)
{
pgoff_t index = offset >> PAGE_SHIFT;
pgoff_t end = DIV_ROUND_UP(offset + length, PAGE_SIZE);
loff_t lastoff = offset;
struct pagevec pvec;
if (length <= 0)
return -ENOENT;
pagevec_init(&pvec);
do {
unsigned nr_pages, i;
nr_pages = pagevec_lookup_range(&pvec, inode->i_mapping, &index,
end - 1);
if (nr_pages == 0)
break;
for (i = 0; i < nr_pages; i++) {
struct page *page = pvec.pages[i];
/*
* At this point, the page may be truncated or
* invalidated (changing page->mapping to NULL), or
* even swizzled back from swapper_space to tmpfs file
* mapping. However, page->index will not change
* because we have a reference on the page.
*
* If current page offset is beyond where we've ended,
* we've found a hole.
*/
if (whence == SEEK_HOLE &&
lastoff < page_offset(page))
goto check_range;
lock_page(page);
if (likely(page->mapping == inode->i_mapping) &&
page_has_buffers(page)) {
lastoff = page_seek_hole_data(page, lastoff, whence);
if (lastoff >= 0) {
unlock_page(page);
goto check_range;
}
}
unlock_page(page);
lastoff = page_offset(page) + PAGE_SIZE;
}
pagevec_release(&pvec);
} while (index < end);
/* When no page at lastoff and we are not done, we found a hole. */
if (whence != SEEK_HOLE)
goto not_found;
check_range:
if (lastoff < offset + length)
goto out;
not_found:
lastoff = -ENOENT;
out:
pagevec_release(&pvec);
return lastoff;
}
void __init buffer_init(void)
{
unsigned long nrpages;

116
fs/iomap.c
View File

@ -20,6 +20,7 @@
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/pagemap.h>
#include <linux/pagevec.h>
#include <linux/file.h>
#include <linux/uio.h>
#include <linux/backing-dev.h>
@ -592,6 +593,121 @@ int iomap_fiemap(struct inode *inode, struct fiemap_extent_info *fi,
}
EXPORT_SYMBOL_GPL(iomap_fiemap);
/*
* Seek for SEEK_DATA / SEEK_HOLE within @page, starting at @lastoff.
*
* Returns the offset within the file on success, and -ENOENT otherwise.
*/
static loff_t
page_seek_hole_data(struct page *page, loff_t lastoff, int whence)
{
loff_t offset = page_offset(page);
struct buffer_head *bh, *head;
bool seek_data = whence == SEEK_DATA;
if (lastoff < offset)
lastoff = offset;
bh = head = page_buffers(page);
do {
offset += bh->b_size;
if (lastoff >= offset)
continue;
/*
* Unwritten extents that have data in the page cache covering
* them can be identified by the BH_Unwritten state flag.
* Pages with multiple buffers might have a mix of holes, data
* and unwritten extents - any buffer with valid data in it
* should have BH_Uptodate flag set on it.
*/
if ((buffer_unwritten(bh) || buffer_uptodate(bh)) == seek_data)
return lastoff;
lastoff = offset;
} while ((bh = bh->b_this_page) != head);
return -ENOENT;
}
/*
* Seek for SEEK_DATA / SEEK_HOLE in the page cache.
*
* Within unwritten extents, the page cache determines which parts are holes
* and which are data: unwritten and uptodate buffer heads count as data;
* everything else counts as a hole.
*
* Returns the resulting offset on successs, and -ENOENT otherwise.
*/
static loff_t
page_cache_seek_hole_data(struct inode *inode, loff_t offset, loff_t length,
int whence)
{
pgoff_t index = offset >> PAGE_SHIFT;
pgoff_t end = DIV_ROUND_UP(offset + length, PAGE_SIZE);
loff_t lastoff = offset;
struct pagevec pvec;
if (length <= 0)
return -ENOENT;
pagevec_init(&pvec);
do {
unsigned nr_pages, i;
nr_pages = pagevec_lookup_range(&pvec, inode->i_mapping, &index,
end - 1);
if (nr_pages == 0)
break;
for (i = 0; i < nr_pages; i++) {
struct page *page = pvec.pages[i];
/*
* At this point, the page may be truncated or
* invalidated (changing page->mapping to NULL), or
* even swizzled back from swapper_space to tmpfs file
* mapping. However, page->index will not change
* because we have a reference on the page.
*
* If current page offset is beyond where we've ended,
* we've found a hole.
*/
if (whence == SEEK_HOLE &&
lastoff < page_offset(page))
goto check_range;
lock_page(page);
if (likely(page->mapping == inode->i_mapping) &&
page_has_buffers(page)) {
lastoff = page_seek_hole_data(page, lastoff, whence);
if (lastoff >= 0) {
unlock_page(page);
goto check_range;
}
}
unlock_page(page);
lastoff = page_offset(page) + PAGE_SIZE;
}
pagevec_release(&pvec);
} while (index < end);
/* When no page at lastoff and we are not done, we found a hole. */
if (whence != SEEK_HOLE)
goto not_found;
check_range:
if (lastoff < offset + length)
goto out;
not_found:
lastoff = -ENOENT;
out:
pagevec_release(&pvec);
return lastoff;
}
static loff_t
iomap_seek_hole_actor(struct inode *inode, loff_t offset, loff_t length,
void *data, struct iomap *iomap)

2
include/linux/buffer_head.h
View File

@ -205,8 +205,6 @@ void write_boundary_block(struct block_device *bdev,
sector_t bblock, unsigned blocksize);
int bh_uptodate_or_lock(struct buffer_head *bh);
int bh_submit_read(struct buffer_head *bh);
loff_t page_cache_seek_hole_data(struct inode *inode, loff_t offset,
loff_t length, int whence);
extern int buffer_heads_over_limit;