git: kernel - Add new bufcache/VM consolidated API, fsx fixes for NFS
dillon at crater.dragonflybsd.org
Tue Jan 19 15:08:05 PST 2010
Author: Matthew Dillon <dillon at apollo.backplane.com>
Date: Tue Jan 19 14:45:46 2010 -0800
kernel - Add new bufcache/VM consolidated API, fsx fixes for NFS
* Add kern/vfs_vm.c with a new API for vtruncbuf() and vnode_pager_setsize()
called nvtruncbuf(), nvextendbuf(), and nvnode_pager_setsize(). This
API solves numerous problems with data coherency between the VM and
buffer cache subsystems.
Generally speaking what this API does is allow the VM pages backing the
buffer straddling EOF in a file to remain valid instead of invalidating
them. Take NFS for example with 32K buffers and, say, a 16385 byte
file. The NFS buffer cache buffer is backed by 8 x 4K VM pages but
the actual file only requires 5 x 4K pages. This API keeps all 8 VM
This API also handles zeroing out portions of the buffer after truncation
and zero-extending portions of the buffer after a file extension.
NFS has been migrated to the new API. HAMMER will soon follow. UFS and
EXT2FS are harder due to their far more complex buffer cache sizing
operations (due to their fragment vs full-sized block handling).
* Remodel the NFS client to use the new API. This allows NFS to consolidate
all truncation and extension operations into nfs_meta_setsize(), including
all code which previously had to deal with special buffer cache / VM
cases related to truncation and extension.
* Fix a bug in kern/vfs_bio.c where NFS buffers requiring the clearing
of B_NEEDCOMMIT failed to also clear B_CLUSTEROK, leading to occassional
attempts by NFS to issue RPCs larger than the NFS I/O block size (resulting
in a panic).
* NFS now uses vop_stdgetpages() and vop_stdputpages(). The NFS-specific
nfs_getpages() and nfs_putpages() has been removed. Remove a vinvalbuf()
in the nfs_bioread() code on remote-directory modification which was
deadlocking getpages. This needs more work.
* Simplify the local-vs-remote modification tests in NFS. This needs more
work. What was happening, generally, was that the larger number of
RPCs inflight allowed by the NFS client was creating too much confusion
in the attribute feedback in the RPC replies, causing the NFS client to
lose track of the file's actual size during heavy modifying operations
(aka fsx tests).
Summary of changes:
sys/conf/files | 1 +
sys/kern/vfs_bio.c | 5 +-
sys/kern/vfs_vm.c | 417 +++++++++++++++++++++++++++++++++++++++++++++++
sys/sys/vnode.h | 5 +
sys/vfs/nfs/nfs.h | 4 +-
sys/vfs/nfs/nfs_bio.c | 382 ++++---------------------------------------
sys/vfs/nfs/nfs_subs.c | 24 ++-
sys/vfs/nfs/nfs_vnops.c | 35 +----
sys/vfs/nfs/nfsnode.h | 2 -
sys/vm/vm_extern.h | 1 -
10 files changed, 481 insertions(+), 395 deletions(-)
create mode 100644 sys/kern/vfs_vm.c
DragonFly BSD source repository
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