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Diffstat (limited to 'fs/iomap/apply.c')
-rw-r--r--fs/iomap/apply.c32
1 files changed, 26 insertions, 6 deletions
diff --git a/fs/iomap/apply.c b/fs/iomap/apply.c
index 54c02aecf3cd..76925b40b5fd 100644
--- a/fs/iomap/apply.c
+++ b/fs/iomap/apply.c
@@ -7,6 +7,7 @@
#include <linux/compiler.h>
#include <linux/fs.h>
#include <linux/iomap.h>
+#include "trace.h"
/*
* Execute a iomap write on a segment of the mapping that spans a
@@ -23,8 +24,12 @@ loff_t
iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
const struct iomap_ops *ops, void *data, iomap_actor_t actor)
{
- struct iomap iomap = { 0 };
+ struct iomap iomap = { .type = IOMAP_HOLE };
+ struct iomap srcmap = { .type = IOMAP_HOLE };
loff_t written = 0, ret;
+ u64 end;
+
+ trace_iomap_apply(inode, pos, length, flags, ops, actor, _RET_IP_);
/*
* Need to map a range from start position for length bytes. This can
@@ -38,7 +43,7 @@ iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
* expose transient stale data. If the reserve fails, we can safely
* back out at this point as there is nothing to undo.
*/
- ret = ops->iomap_begin(inode, pos, length, flags, &iomap);
+ ret = ops->iomap_begin(inode, pos, length, flags, &iomap, &srcmap);
if (ret)
return ret;
if (WARN_ON(iomap.offset > pos))
@@ -46,19 +51,34 @@ iomap_apply(struct inode *inode, loff_t pos, loff_t length, unsigned flags,
if (WARN_ON(iomap.length == 0))
return -EIO;
+ trace_iomap_apply_dstmap(inode, &iomap);
+ if (srcmap.type != IOMAP_HOLE)
+ trace_iomap_apply_srcmap(inode, &srcmap);
+
/*
* Cut down the length to the one actually provided by the filesystem,
* as it might not be able to give us the whole size that we requested.
*/
- if (iomap.offset + iomap.length < pos + length)
- length = iomap.offset + iomap.length - pos;
+ end = iomap.offset + iomap.length;
+ if (srcmap.type != IOMAP_HOLE)
+ end = min(end, srcmap.offset + srcmap.length);
+ if (pos + length > end)
+ length = end - pos;
/*
- * Now that we have guaranteed that the space allocation will succeed.
+ * Now that we have guaranteed that the space allocation will succeed,
* we can do the copy-in page by page without having to worry about
* failures exposing transient data.
+ *
+ * To support COW operations, we read in data for partially blocks from
+ * the srcmap if the file system filled it in. In that case we the
+ * length needs to be limited to the earlier of the ends of the iomaps.
+ * If the file system did not provide a srcmap we pass in the normal
+ * iomap into the actors so that they don't need to have special
+ * handling for the two cases.
*/
- written = actor(inode, pos, length, data, &iomap);
+ written = actor(inode, pos, length, data, &iomap,
+ srcmap.type != IOMAP_HOLE ? &srcmap : &iomap);
/*
* Now the data has been copied, commit the range we've copied. This