Page MenuHomeFreeBSD
Files F115832092

D29637.diff
No OneTemporary
Actions

D29637.diff
View Options

diff --git a/share/man/man9/vnode_pager_setsize.9 b/share/man/man9/vnode_pager_setsize.9
--- a/share/man/man9/vnode_pager_setsize.9
+++ b/share/man/man9/vnode_pager_setsize.9
@@ -27,7 +27,7 @@
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
-.Dd April 6, 2021
+.Dd April 8, 2021
.Dt VNODE_PAGER_SETSIZE 9
.Os
.Sh NAME
@@ -41,26 +41,31 @@
.Fn vnode_pager_setsize "struct vnode *vp" "vm_ooffset_t nsize"
.Sh DESCRIPTION
.Nm
-lets the VM system know about a change in size for a file.
-Content beyond the new EOF specified by the
-.Fa nsize
-argument will be purged from the cache.
-This function is useful for use within file system code to implement
-truncation in
-.Xr VOP_SETATTR 9 .
-.Sh IMPLEMENTATION NOTES
+lets the VM system know about a change in size for a file,
+and updates the object size and vnode pager size of the vm object in
+.Fa vp
+with
+.Fa nsize .
+Page faults on the object mapping with offset beyond the new object
+size results in
+.Va SIGBUS .
+.Pp
+Pages between the old EOF and the new EOF are removed from the object queue
+if the file size shrinks.
In case the new EOF specified by the
.Fa nsize
-argument is not aligned to page boundaries,
-partial-page area starting beyond the EOF will be zeroed.
-In partial-page area,
-for content occupying whole blocks within block
-boundaries,
-the dirty bits for the corresponding blocks will be cleared.
-.Sh LOCKING
-Writer lock of the VM object of
+argument is not aligned to page boundary,
+partial-page area starting beyond the EOF is zeroed and marked invalid.
+if the page exists resident.
+.Pp
+In case the vnode
.Fa vp
-will be held within the function.
+does not have a VM object allocated, the effect of calling this function is no-op.
+.Pp
+This function must be used within file system code to implement truncation
+if the file system allocates vm objects for vnodes.
+.Sh LOCKS
+The vnode should be exclusively locked on entry and will still be locked on exit.
.Sh SEE ALSO
.Xr vnode 9
.Sh HISTORY

File Metadata

Mime Type
text/plain
Expires
Wed, Apr 30, 7:29 AM (16 h, 27 m)
Storage Engine
blob
Storage Format
Raw Data
Storage Handle
17853491
Default Alt Text
D29637.diff (1 KB)

Event Timeline