https://github.com/torvalds/linux
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
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
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
Btrfs: pwrite blocked when writing from the mmaped buffer of the same page
Tip revision: 914ee29
Kconfig
config JFS_FS
tristate "JFS filesystem support"
select NLS
select CRC32
help
This is a port of IBM's Journaled Filesystem . More information is
available in the file <file:Documentation/filesystems/jfs.txt>.
If you do not intend to use the JFS filesystem, say N.
config JFS_POSIX_ACL
bool "JFS POSIX Access Control Lists"
depends on JFS_FS
select FS_POSIX_ACL
help
Posix Access Control Lists (ACLs) support permissions for users and
groups beyond the owner/group/world scheme.
To learn more about Access Control Lists, visit the Posix ACLs for
Linux website <http://acl.bestbits.at/>.
If you don't know what Access Control Lists are, say N
config JFS_SECURITY
bool "JFS Security Labels"
depends on JFS_FS
help
Security labels support alternative access control models
implemented by security modules like SELinux. This option
enables an extended attribute handler for file security
labels in the jfs filesystem.
If you are not using a security module that requires using
extended attributes for file security labels, say N.
config JFS_DEBUG
bool "JFS debugging"
depends on JFS_FS
help
If you are experiencing any problems with the JFS filesystem, say
Y here. This will result in additional debugging messages to be
written to the system log. Under normal circumstances, this
results in very little overhead.
config JFS_STATISTICS
bool "JFS statistics"
depends on JFS_FS
help
Enabling this option will cause statistics from the JFS file system
to be made available to the user in the /proc/fs/jfs/ directory.
Computing file changes ...