The branch main has been updated by khng:
URL:
https://cgit.FreeBSD.org/src/commit/?id=1eaa36523cb921e90d61b20531ed525aba0cfe7e
commit 1eaa36523cb921e90d61b20531ed525aba0cfe7e
Author: Ka Ho Ng <k...@freebsd.org>
AuthorDate: 2021-08-24 09:04:02 +0000
Commit: Ka Ho Ng <k...@freebsd.org>
CommitDate: 2021-08-24 09:08:28 +0000
fspacectl(2): Clarifies the return values
rmacklem@ spotted two things in the system call:
- Upon returning from a successful operation, vop_stddeallocate can
update rmsr.r_offset to a value greater than file size. This behavior,
although being harmless, can be confusing.
- The EINVAL return value for rqsr.r_offset + rqsr.r_len > OFF_MAX is
undocumented.
This commit has the following changes:
- vop_stddeallocate and shm_deallocate to bound the the affected area
further by the file size.
- The EINVAL case for rqsr.r_offset + rqsr.r_len > OFF_MAX is
documented.
- The fspacectl(2), vn_deallocate(9) and VOP_DEALLOCATE(9)'s return
len is explicitly documented the be the value 0, and the return offset
is restricted to be the smallest of off + len and current file size
suggested by kib@. This semantic allows callers to interact better
with potential file size growth after the call.
Sponsored by: The FreeBSD Foundation
Reviewed by: imp, kib
Differential Revision: https://reviews.freebsd.org/D31604
---
lib/libc/sys/fspacectl.2 | 27 ++++++++++++++++++++++-----
share/man/man9/VOP_DEALLOCATE.9 | 8 ++++++++
share/man/man9/vn_deallocate.9 | 8 ++++++++
sys/kern/uipc_shm.c | 11 +++++++++--
sys/kern/vfs_default.c | 8 ++++++--
5 files changed, 53 insertions(+), 9 deletions(-)
diff --git a/lib/libc/sys/fspacectl.2 b/lib/libc/sys/fspacectl.2
index 2f581d1c1fb8..0e369785b883 100644
--- a/lib/libc/sys/fspacectl.2
+++ b/lib/libc/sys/fspacectl.2
@@ -27,7 +27,7 @@
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
-.Dd August 4, 2021
+.Dd August 18, 2021
.Dt FSPACECTL 2
.Os
.Sh NAME
@@ -67,6 +67,17 @@ argument is non-NULL, the
.Fa spacectl_range
structure it points to is updated to contain the unprocessed operation range
after the system call returns.
+.Pp
+For a successful completion without an unprocessed part in the requested
+operation range,
+.Fa "rmsr->r_len"
+is updated to be the value 0, and
+.Fa "rmsr->r_offset"
+is updated to be the smallest of
+.Fa "rqsr->r_offset" +
+.Fa "rqsr->r_len" ;
+and the end-of-file offset.
+The file descriptor's file offset is not used or modified by the system call.
Both
.Fa rqsr
and
@@ -92,9 +103,9 @@ Zero a region in the file specified by the
.Fa rqsr
argument.
The
-.Va "rqsr->r_offset"
+.Fa "rqsr->r_offset"
has to be a value greater than or equal to 0, and the
-.Va "rqsr->r_len"
+.Fa "rqsr->r_len"
has to be a value greater than 0.
.Pp
If the file system supports hole-punching,
@@ -132,11 +143,17 @@ If the
argument is
.Dv SPACECTL_DEALLOC ,
either the
-.Fa "range->r_offset"
+.Fa "rqsr->r_offset"
argument was less than zero, or the
-.Fa "range->r_len"
+.Fa "rqsr->r_len"
argument was less than or equal to zero.
.It Bq Er EINVAL
+The value of
+.Fa "rqsr->r_offset" +
+.Fa "rqsr->r_len"
+is greater than
+.Dv OFF_MAX .
+.It Bq Er EINVAL
An invalid or unsupported flag is included in
.Fa flags .
.It Bq Er EINVAL
diff --git a/share/man/man9/VOP_DEALLOCATE.9 b/share/man/man9/VOP_DEALLOCATE.9
index dbfe048f2235..2ec915c6fef3 100644
--- a/share/man/man9/VOP_DEALLOCATE.9
+++ b/share/man/man9/VOP_DEALLOCATE.9
@@ -74,6 +74,14 @@ and
are updated to reflect the portion of the range that
still needs to be zeroed/deallocated on return.
Partial result is considered a successful operation.
+For a successful completion without an unprocessed portion of the range,
+.Fa *len
+is updated to be the value 0, and
+.Fa *offset
+is updated to be the smallest of
+.Fa *offset +
+.Fa *len
+passed to the call and the end-of-file offset.
.Sh LOCKS
The vnode should be locked on entry and will still be locked on exit.
.Sh RETURN VALUES
diff --git a/share/man/man9/vn_deallocate.9 b/share/man/man9/vn_deallocate.9
index 29edcd57ff5d..08f4e92ec597 100644
--- a/share/man/man9/vn_deallocate.9
+++ b/share/man/man9/vn_deallocate.9
@@ -95,6 +95,14 @@ Attempt to bypass buffer cache.
and
.Fa *length
are updated to reflect the unprocessed operation range of the call.
+For a successful completion,
+.Fa *length
+is updated to be the value 0, and
+.Fa *offset
+is updated to be the smallest of
+.Fa *offset +
+.Fa *length
+passed to the call and the end-of-file offset.
.Sh RETURN VALUES
Upon successful completion, the value 0 is returned; otherwise the
appropriate error is returned.
diff --git a/sys/kern/uipc_shm.c b/sys/kern/uipc_shm.c
index 16d1e22a898b..60815ef24c26 100644
--- a/sys/kern/uipc_shm.c
+++ b/sys/kern/uipc_shm.c
@@ -1905,6 +1905,8 @@ shm_deallocate(struct shmfd *shmfd, off_t *offset, off_t
*length, int flags)
off = *offset;
len = *length;
KASSERT(off + len <= (vm_ooffset_t)OFF_MAX, ("off + len overflows"));
+ if (off + len > shmfd->shm_size)
+ len = shmfd->shm_size - off;
object = shmfd->shm_object;
startofs = off & PAGE_MASK;
endofs = (off + len) & PAGE_MASK;
@@ -1913,6 +1915,13 @@ shm_deallocate(struct shmfd *shmfd, off_t *offset, off_t
*length, int flags)
pi = OFF_TO_IDX(off + PAGE_MASK);
error = 0;
+ /* Handle the case when offset is beyond shm size */
+ if ((off_t)len < 0) {
+ *offset = shmfd->shm_size;
+ *length = 0;
+ return (0);
+ }
+
VM_OBJECT_WLOCK(object);
if (startofs != 0) {
@@ -1974,8 +1983,6 @@ shm_fspacectl(struct file *fp, int cmd, off_t *offset,
off_t *length, int flags,
break;
}
error = shm_deallocate(shmfd, &off, &len, flags);
- if (error != 0)
- break;
*offset = off;
*length = len;
break;
diff --git a/sys/kern/vfs_default.c b/sys/kern/vfs_default.c
index d9328cd39b00..d5df9cd8bf7b 100644
--- a/sys/kern/vfs_default.c
+++ b/sys/kern/vfs_default.c
@@ -1138,14 +1138,13 @@ vop_stddeallocate(struct vop_deallocate_args *ap)
vp = ap->a_vp;
offset = *ap->a_offset;
- len = *ap->a_len;
cred = ap->a_cred;
error = VOP_GETATTR(vp, &va, cred);
if (error)
return (error);
- len = omin(OFF_MAX - offset, *ap->a_len);
+ len = omin((off_t)va.va_size - offset, *ap->a_len);
while (len > 0) {
noff = offset;
error = vn_bmap_seekhole_locked(vp, FIOSEEKDATA, &noff, cred);
@@ -1185,6 +1184,11 @@ vop_stddeallocate(struct vop_deallocate_args *ap)
if (should_yield())
break;
}
+ /* Handle the case when offset is beyond EOF */
+ if (len < 0) {
+ offset += len;
+ len = 0;
+ }
out:
*ap->a_offset = offset;
*ap->a_len = len;
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