quoted

quoted

quoted

quoted

Andrew Morton (AM) writes:

 AM> That's correct.  Reads are usually synchronous and writes are
 AM> rarely synchronous.

 AM> The most common place where the kernel forces a user process to
 AM> wait on completion of a write is actually in unlink (truncate,
 AM> really).  Because truncate must wait for in-progress I/O to
 AM> complete before allowing the filesystem to free (and potentially
 AM> reuse) the affected blocks.

looks like I miss something here.

why do wait for write completion in truncate? 

getblk (blockmap);
getblk (bitmap);
set 0 in blockmap->b_data[N];
mark_buffer_dirty (blockmap);
clear_bit (N, &bitmap);
mark_buffer_dirty (bitmap);

isn't that enough?

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