blocks of zeros could wind up in a file written to over NFS by a client. The problem only occurs a few times per several gigabytes of data. This problem turned out to be bug #3 below. bug #1: B_CLUSTEROK must be cleared when an NFS buffer is reverted from stage 2 (ready for commit rpc) to stage 1 (ready for write). Reversions can occur when a dirty NFS buffer is redirtied with new data. Otherwise the VFS/BIO system may end up thinking that a stage 1 NFS buffer is clusterable. Stage 1 NFS buffers are not clusterable. bug #2: B_CLUSTEROK was inappropriately set for a 'short' NFS buffer (short buffers only occur near the EOF of the file). Change to only set when the buffer is a full biosize (usually 8K). This bug has no effect but should be fixed in -current anyway. It need not be backported. bug #3: B_NEEDCOMMIT was inappropriately set in nfs_flush() (which is typically only called by the update daemon). nfs_flush() does a multi-pass loop but due to the lack of vnode locking it is possible for new buffers to be added to the dirtyblkhd list while a flush operation is going on. This may result in nfs_flush() setting B_NEEDCOMMIT on a buffer which has *NOT* yet gone through its stage 1 write, causing only the commit rpc to be made and thus causing the contents of the buffer to be thrown away (never sent to the server). The patch also contains some cleanup, which only applies to the commit into -current. Reviewed by: dg, julian Originally Reported by: Dan Nelson <dnelson@emsphone.com> |
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.. | ||
nfs_serv.c | ||
nfs_srvcache.c | ||
nfs_srvsock.c | ||
nfs_srvsubs.c | ||
nfs_syscalls.c | ||
nfs.h | ||
nfsm_subs.h | ||
nfsproto.h | ||
nfsrvcache.h | ||
nfsrvstats.h |