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authorJosef Bacik <josef@redhat.com>2011-07-17 04:44:56 +0400
committerAl Viro <viro@zeniv.linux.org.uk>2011-07-21 04:47:59 +0400
commit02c24a82187d5a628c68edfe71ae60dc135cd178 (patch)
treec8dbaba4d82e2b20ed4335910a564a1f7d90fcf6 /Documentation/filesystems/porting
parent22735068d53c7115e384bc88dea95b17e76a6839 (diff)
downloadlinux-02c24a82187d5a628c68edfe71ae60dc135cd178.tar.xz
fs: push i_mutex and filemap_write_and_wait down into ->fsync() handlers
Btrfs needs to be able to control how filemap_write_and_wait_range() is called in fsync to make it less of a painful operation, so push down taking i_mutex and the calling of filemap_write_and_wait() down into the ->fsync() handlers. Some file systems can drop taking the i_mutex altogether it seems, like ext3 and ocfs2. For correctness sake I just pushed everything down in all cases to make sure that we keep the current behavior the same for everybody, and then each individual fs maintainer can make up their mind about what to do from there. Thanks, Acked-by: Jan Kara <jack@suse.cz> Signed-off-by: Josef Bacik <josef@redhat.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'Documentation/filesystems/porting')
-rw-r--r--Documentation/filesystems/porting7
1 files changed, 7 insertions, 0 deletions
diff --git a/Documentation/filesystems/porting b/Documentation/filesystems/porting
index 6b96773e27cb..7f8861d341ea 100644
--- a/Documentation/filesystems/porting
+++ b/Documentation/filesystems/porting
@@ -421,3 +421,10 @@ data and there is a virtual hole at the end of the file. So if the provided
offset is less than i_size and SEEK_DATA is specified, return the same offset.
If the above is true for the offset and you are given SEEK_HOLE, return the end
of the file. If the offset is i_size or greater return -ENXIO in either case.
+
+[mandatory]
+ If you have your own ->fsync() you must make sure to call
+filemap_write_and_wait_range() so that all dirty pages are synced out properly.
+You must also keep in mind that ->fsync() is not called with i_mutex held
+anymore, so if you require i_mutex locking you must make sure to take it and
+release it yourself.