From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Simmons Date: Thu, 27 Feb 2020 16:14:50 -0500 Subject: [lustre-devel] [PATCH 422/622] lustre: lov: Correct write_intent end for trunc In-Reply-To: <1582838290-17243-1-git-send-email-jsimmons@infradead.org> References: <1582838290-17243-1-git-send-email-jsimmons@infradead.org> Message-ID: <1582838290-17243-423-git-send-email-jsimmons@infradead.org> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: lustre-devel@lists.lustre.org From: Patrick Farrell When instantiating a layout, the server interprets the write intent from the client as the range [start, end), not including the last byte. This is correct for writes because the last byte given for a write is actually 'endpos', the resulting file pointer position, and so is not included. However, truncate is specifying a size, not an endpos, so truncate is [start, size]. To make this work with the [start, end) processing for write_intents, we have to add 1 to the size when sending a write intent. Without this, a truncate operation to the first byte of a new layout component fails silently because the component is not instantiated. WC-bug-id: https://jira.whamcloud.com/browse/LU-12586 Lustre-commit: c32c7401426d ("LU-12586 lov: Correct write_intent end for trunc") Signed-off-by: Patrick Farrell Reviewed-on: https://review.whamcloud.com/35607 Reviewed-by: Andreas Dilger Reviewed-by: Mike Pershin Reviewed-by: Oleg Drokin Signed-off-by: James Simmons --- fs/lustre/lov/lov_io.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/fs/lustre/lov/lov_io.c b/fs/lustre/lov/lov_io.c index 9328240..6e86efa 100644 --- a/fs/lustre/lov/lov_io.c +++ b/fs/lustre/lov/lov_io.c @@ -555,7 +555,15 @@ static int lov_io_slice_init(struct lov_io *lio, struct lov_object *obj, */ if (cl_io_is_trunc(io)) { io->ci_write_intent.e_start = 0; - io->ci_write_intent.e_end = io->u.ci_setattr.sa_attr.lvb_size; + /* for writes, e_end is endpos, the location of the file + * pointer after the write is completed, so it is not accessed. + * For truncate, 'end' is the size, and *is* acccessed. + * In other words, writes are [start, end), but truncate is + * [start, size], where both are included. So add 1 to the + * size when creating the write intent to account for this. + */ + io->ci_write_intent.e_end = + io->u.ci_setattr.sa_attr.lvb_size + 1; } else { io->ci_write_intent.e_start = lio->lis_pos; io->ci_write_intent.e_end = lio->lis_endpos; -- 1.8.3.1