SYNC_FILE_RANGE_WRITE may and will block. Document that.

[[email protected]: fix comment text]
Signed-off-by: Pavel Machek <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

diff --git a/fs/sync.c b/fs/sync.c
index 228e17b5e9ee911c2c2f58b4090e33b96954ff23..2967562d416fb52e54a1af5840d0dc63c0d25cfb 100644 (file)
--- a/fs/sync.c
+++ b/fs/sync.c
@@ -139,7 +139,8 @@ asmlinkage long sys_fdatasync(unsigned int fd)
  * before performing the write.
  *
  * SYNC_FILE_RANGE_WRITE: initiate writeout of all those dirty pages in the
- * range which are not presently under writeback.
+ * range which are not presently under writeback. Note that this may block for
+ * significant periods due to exhaustion of disk request structures.
  *
  * SYNC_FILE_RANGE_WAIT_AFTER: wait upon writeout of all pages in the range
  * after performing the write.