LU-12586 lov: Correct write_intent end for trunc

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 specifiying 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.

Signed-off-by: Patrick Farrell <pfarrell@whamcloud.com>
Change-Id: Id2b07abe73455bf1f0ed841ad08c5f381a871315
Reviewed-on: https://review.whamcloud.com/35607
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Mike Pershin <mpershin@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>

diff --git a/lustre/lov/lov_io.c b/lustre/lov/lov_io.c
index d67dfa7..4a93214 100644 (file)
--- a/lustre/lov/lov_io.c
+++ b/lustre/lov/lov_io.c
@@ -566,7 +566,15 @@ static int lov_io_slice_init(struct lov_io *lio,
         */
        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;

diff --git a/lustre/tests/sanity-pfl.sh b/lustre/tests/sanity-pfl.sh
index 517bc1d..83ac42b 100644 (file)
--- a/lustre/tests/sanity-pfl.sh
+++ b/lustre/tests/sanity-pfl.sh
@@ -528,7 +528,8 @@ test_11() {
        [[ -n $f4 ]] && error "1: 4th component instantiated"
 
        # the first 2 components instantiated
-       $TRUNCATE $comp_file $((1024*1024*1+1))
+       # Truncate to exact start of new component - LU-12586
+       $TRUNCATE $comp_file $((1024*1024*1))
 
        f2=$($LFS getstripe -I2 $comp_file | grep "l_fid")
        [[ -z $f2 ]] && error "2: 2nd component uninstantiated"
@@ -538,7 +539,7 @@ test_11() {
        [[ -n $f4 ]] && error "2: 4th component instantiated"
 
        # the first 3 components instantiated
-       $TRUNCATE $comp_file $((1024*1024*3))
+       $TRUNCATE $comp_file $((1024*1024*3 - 1))
        $TRUNCATE $comp_file $((1024*1024*1+1))
 
        f2=$($LFS getstripe -I2 $comp_file | grep "l_fid")