nilfs2: avoid duplicate segment construction for fsync()
This patch removes filemap_write_and_wait_range() from nilfs_sync_file(),
because it triggers a data segment construction by calling
nilfs_writepages() with WB_SYNC_ALL. A data segment construction does not
remove the inode from the i_dirty list and it does not clear the
NILFS_I_DIRTY flag. Therefore nilfs_inode_dirty() still returns true,
which leads to an unnecessary duplicate segment construction in
nilfs_sync_file().
A call to filemap_write_and_wait_range() is not needed, because NILFS2
does not rely on the generic writeback mechanisms. Instead it implements
its own mechanism to collect all dirty pages and write them into segments.
It is more efficient to initiate the segment construction directly in
nilfs_sync_file() without the detour over filemap_write_and_wait_range().
Additionally the lock of i_mutex is not needed, because all code blocks
that are protected by i_mutex are also protected by a NILFS transaction:
For nilfs_lookup() i_mutex is held for the parent directory, to protect it
from modification. The segment construction does not modify directory
inodes, so no lock is needed.
nilfs_fiemap() reads the block layout on the disk, by using
nilfs_bmap_lookup_contig(). This is already protected by bmap->b_sem.
Signed-off-by: Andreas Rohner <andreas.rohner@gmx.net> Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>