From: Darrick J. Wong <djwong@xxxxxxxxxx>
The predicate code that iomap_unshare_iter uses to decide if it's really
needs to unshare a file range mapping should be shared with the fsdax
version, because right now they're opencoded and inconsistent.
Note that we simplify the predicate logic a bit -- we no longer allow
unsharing of inline data mappings, but there aren't any filesystems that
allow shared inline data currently.
This is a fix in the sense that it should have been ported to fsdax.
Fixes: b53fdb215d13 ("iomap: improve shared block detection in iomap_unshare_iter")
Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
---
fs/dax.c | 3 +--
fs/iomap/buffered-io.c | 30 ++++++++++++++++--------------
include/linux/iomap.h | 1 +
3 files changed, 18 insertions(+), 16 deletions(-)
diff --git a/fs/dax.c b/fs/dax.c
index c62acd2812f8..5064eefb1c1e 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1268,8 +1268,7 @@ static s64 dax_unshare_iter(struct iomap_iter *iter)
s64 ret = 0;
void *daddr = NULL, *saddr = NULL;
- /* don't bother with blocks that are not shared to start with */
- if (!(iomap->flags & IOMAP_F_SHARED))
+ if (!iomap_want_unshare_iter(iter))
return length;
id = dax_read_lock();
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 78ebd265f425..3899169b2cf7 100644
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1309,19 +1309,12 @@ void iomap_file_buffered_write_punch_delalloc(struct inode *inode,
}
EXPORT_SYMBOL_GPL(iomap_file_buffered_write_punch_delalloc);
-static loff_t iomap_unshare_iter(struct iomap_iter *iter)
+bool iomap_want_unshare_iter(const struct iomap_iter *iter)
{
- struct iomap *iomap = &iter->iomap;
- loff_t pos = iter->pos;
- loff_t length = iomap_length(iter);
- loff_t written = 0;
-
- /* Don't bother with blocks that are not shared to start with. */
- if (!(iomap->flags & IOMAP_F_SHARED))
- return length;
-
/*
- * Don't bother with delalloc reservations, holes or unwritten extents.
+ * Don't bother with blocks that are not shared to start with; or
+ * mappings that cannot be shared, such as inline data, delalloc
+ * reservations, holes or unwritten extents.
*
* Note that we use srcmap directly instead of iomap_iter_srcmap as
* unsharing requires providing a separate source map, and the presence
@@ -1329,9 +1322,18 @@ static loff_t iomap_unshare_iter(struct iomap_iter *iter)
* IOMAP_F_SHARED which can be set for any data that goes into the COW
* fork for XFS.
*/
- if (iter->srcmap.type == IOMAP_HOLE ||
- iter->srcmap.type == IOMAP_DELALLOC ||
- iter->srcmap.type == IOMAP_UNWRITTEN)
+ return (iter->iomap.flags & IOMAP_F_SHARED) &&
+ iter->srcmap.type == IOMAP_MAPPED;
+}
+
+static loff_t iomap_unshare_iter(struct iomap_iter *iter)
+{
+ struct iomap *iomap = &iter->iomap;
+ loff_t pos = iter->pos;
+ loff_t length = iomap_length(iter);
+ loff_t written = 0;
+
+ if (!iomap_want_unshare_iter(iter))
return length;
do {
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 4ad12a3c8bae..d8a7fc84348c 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -267,6 +267,7 @@ void iomap_invalidate_folio(struct folio *folio, size_t offset, size_t len);
bool iomap_dirty_folio(struct address_space *mapping, struct folio *folio);
int iomap_file_unshare(struct inode *inode, loff_t pos, loff_t len,
const struct iomap_ops *ops);
+bool iomap_want_unshare_iter(const struct iomap_iter *iter);
int iomap_zero_range(struct inode *inode, loff_t pos, loff_t len,
bool *did_zero, const struct iomap_ops *ops);
int iomap_truncate_page(struct inode *inode, loff_t pos, bool *did_zero,
