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authorChristoph Hellwig <hch@lst.de>2019-10-18 16:42:50 -0700
committerDarrick J. Wong <darrick.wong@oracle.com>2019-10-21 08:51:59 -0700
commit32a38a4991043976fc2d8840a55ce5dde41fdbd0 (patch)
treeaa722afa19ce30a6cf62a3f7814f2d0052f13391 /fs/iomap
parentd3b404396977fde1daca3fb4fd4d3b01a3749093 (diff)
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iomap: use write_begin to read pages to unshare
Use the existing iomap write_begin code to read the pages unshared by iomap_file_unshare. That avoids the extra ->readpage call and extent tree lookup currently done by read_mapping_page. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Diffstat (limited to 'fs/iomap')
-rw-r--r--fs/iomap/buffered-io.c49
1 files changed, 16 insertions, 33 deletions
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 7e9d7fdaae49..b61076823544 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -548,6 +548,10 @@ iomap_migrate_page(struct address_space *mapping, struct page *newpage,
EXPORT_SYMBOL_GPL(iomap_migrate_page);
#endif /* CONFIG_MIGRATION */
+enum {
+ IOMAP_WRITE_F_UNSHARE = (1 << 0),
+};
+
static void
iomap_write_failed(struct inode *inode, loff_t pos, unsigned len)
{
@@ -577,7 +581,7 @@ iomap_read_page_sync(loff_t block_start, struct page *page, unsigned poff,
}
static int
-__iomap_write_begin(struct inode *inode, loff_t pos, unsigned len,
+__iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, int flags,
struct page *page, struct iomap *iomap)
{
struct iomap_page *iop = iomap_page_create(inode, page);
@@ -596,11 +600,14 @@ __iomap_write_begin(struct inode *inode, loff_t pos, unsigned len,
if (plen == 0)
break;
- if ((from <= poff || from >= poff + plen) &&
+ if (!(flags & IOMAP_WRITE_F_UNSHARE) &&
+ (from <= poff || from >= poff + plen) &&
(to <= poff || to >= poff + plen))
continue;
if (iomap_block_needs_zeroing(inode, iomap, block_start)) {
+ if (WARN_ON_ONCE(flags & IOMAP_WRITE_F_UNSHARE))
+ return -EIO;
zero_user_segments(page, poff, from, to, poff + plen);
iomap_set_range_uptodate(page, poff, plen);
continue;
@@ -646,7 +653,8 @@ iomap_write_begin(struct inode *inode, loff_t pos, unsigned len, unsigned flags,
else if (iomap->flags & IOMAP_F_BUFFER_HEAD)
status = __block_write_begin_int(page, pos, len, NULL, iomap);
else
- status = __iomap_write_begin(inode, pos, len, page, iomap);
+ status = __iomap_write_begin(inode, pos, len, flags, page,
+ iomap);
if (unlikely(status))
goto out_unlock;
@@ -869,22 +877,6 @@ iomap_file_buffered_write(struct kiocb *iocb, struct iov_iter *iter,
}
EXPORT_SYMBOL_GPL(iomap_file_buffered_write);
-static struct page *
-__iomap_read_page(struct inode *inode, loff_t offset)
-{
- struct address_space *mapping = inode->i_mapping;
- struct page *page;
-
- page = read_mapping_page(mapping, offset >> PAGE_SHIFT, NULL);
- if (IS_ERR(page))
- return page;
- if (!PageUptodate(page)) {
- put_page(page);
- return ERR_PTR(-EIO);
- }
- return page;
-}
-
static loff_t
iomap_unshare_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
struct iomap *iomap)
@@ -900,24 +892,15 @@ iomap_unshare_actor(struct inode *inode, loff_t pos, loff_t length, void *data,
return length;
do {
- struct page *page, *rpage;
- unsigned long offset; /* Offset into pagecache page */
- unsigned long bytes; /* Bytes to write to page */
-
- offset = offset_in_page(pos);
- bytes = min_t(loff_t, PAGE_SIZE - offset, length);
-
- rpage = __iomap_read_page(inode, pos);
- if (IS_ERR(rpage))
- return PTR_ERR(rpage);
+ unsigned long offset = offset_in_page(pos);
+ unsigned long bytes = min_t(loff_t, PAGE_SIZE - offset, length);
+ struct page *page;
- status = iomap_write_begin(inode, pos, bytes, 0, &page, iomap);
- put_page(rpage);
+ status = iomap_write_begin(inode, pos, bytes,
+ IOMAP_WRITE_F_UNSHARE, &page, iomap);
if (unlikely(status))
return status;
- WARN_ON_ONCE(!PageUptodate(page));
-
status = iomap_write_end(inode, pos, bytes, bytes, page, iomap);
if (unlikely(status <= 0)) {
if (WARN_ON_ONCE(status == 0))