On Tue, May 24, 2011 at 7:30 AM, Eric Sandeen <sandeen@xxxxxxxxxx> wrote: > On 5/23/11 2:19 PM, Theodore Ts'o wrote: >> In commit c8d46e41 (ext4: Add flag to files with blocks intentionally >> past EOF), if the EOFBLOCKS_FL flag is set, we call ext4_truncate() >> before calling vmtruncate(). This caused any allocated but unwritten >> blocks created by calling fallocate() with the FALLOC_FL_KEEP_SIZE >> flag to be dropped. This was done to make to make sure that >> EOFBLOCKS_FL would not be cleared while still leaving blocks past >> i_size allocated. This was not necessary, since ext4_truncate() >> guarantees that blocks past i_size will be dropped, even in the case >> where truncate() has increased i_size before calling ext4_truncate(). >> >> So fix this by removing the EOFBLOCKS_FL special case treatment in >> ext4_setattr(). In addition, use truncate_setsize() followed by a >> call to ext4_truncate() instead of using vmtruncate(). This is more >> efficient since it skips the call to inode_newsize_ok(), which has >> been checked already by inode_change_ok(). This is also in a win in >> the case where EOFBLOCKS_FL is set since it avoids calling >> ext4_truncate() twice. >> >> Signed-off-by: "Theodore Ts'o" <tytso@xxxxxxx> >> --- >> Jiayingz pointed out that in the case where we fallocate 12k, write 4k, and >> then truncate to 4k, we should discard the excess fallocate'd blocks. So if >> attr->ia_size == inode.i_size, we can skip the truncate_setsize() call, but >> if the EOFBLOCKS_FL flag is set, we should still call ext4_truncate(). > > are there xfstests which cover this explicitly? It should be simple to write. > Vivek has written a xfstest to cover this and more fallocate/truncate cases: http://old.nabble.com/-PATCH--xfstests%3A-test-fallocate%2C-write%2C-ftruncate-combinations.-to31666685.html#a31666685 Jiaying > If filesystem behavior differs we can always make ext4-only tests. > > -Eric > -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
