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23 October 2021, 00:29:24 UTC
Revision 914ee295af418e936ec20a08c1663eaabe4cd07a authored by Xin Zhong on 09 December 2010, 09:30:14 UTC, committed by Chris Mason on 10 December 2010, 21:29:10 UTC 
Btrfs: pwrite blocked when writing from the mmaped buffer of the same page
 
This problem is found in meego testing:
http://bugs.meego.com/show_bug.cgi?id=6672
A file in btrfs is mmaped and the mmaped buffer is passed to pwrite to write to the same page
of the same file. In btrfs_file_aio_write(), the pages is locked by prepare_pages(). So when
btrfs_copy_from_user() is called, page fault happens and the same page needs to be locked again
in filemap_fault(). The fix is to move iov_iter_fault_in_readable() before prepage_pages() to make page
fault happen before pages are locked. And also disable page fault in critical region in
btrfs_copy_from_user().

Reviewed-by: Yan, Zheng<zheng.z.yan@intel.com>
Signed-off-by: Zhong, Xin <xin.zhong@intel.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
1 parent f106e82
History
Tip revision: 914ee295af418e936ec20a08c1663eaabe4cd07a authored by Xin Zhong on 09 December 2010, 09:30:14 UTC
Btrfs: pwrite blocked when writing from the mmaped buffer of the same page
Tip revision: 914ee29
File Mode Size
ChangeLog -rw-r--r-- 14.0 KB
Kconfig -rw-r--r-- 948 bytes
Makefile -rw-r--r-- 164 bytes
TODO -rw-r--r-- 385 bytes
befs.h -rw-r--r-- 3.2 KB
befs_fs_types.h -rw-r--r-- 4.9 KB
btree.c -rw-r--r-- 21.9 KB
btree.h -rw-r--r-- 300 bytes
datastream.c -rw-r--r-- 15.5 KB
datastream.h -rw-r--r-- 514 bytes
debug.c -rw-r--r-- 7.6 KB
endian.h -rw-r--r-- 3.1 KB
inode.c -rw-r--r-- 1.1 KB
inode.h -rw-r--r-- 123 bytes
io.c -rw-r--r-- 1.8 KB
io.h -rw-r--r-- 190 bytes
linuxvfs.c -rw-r--r-- 24.0 KB
super.c -rw-r--r-- 3.0 KB
super.h -rw-r--r-- 134 bytes
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