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fs: push i_mutex and filemap_write_and_wait down into ->fsync() handlers

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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>
This commit is contained in:
Josef Bacik
2011-07-16 20:44:56 -04:00
committed by Al Viro
parent 22735068d5
commit 02c24a8218
71 changed files with 462 additions and 164 deletions
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Documentation/filesystems/porting
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@@ -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.