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On Thu, Apr 25, 2024 at 07:49:23PM -0700, Rick Macklem wrote: > Hi, > > This week I have been doing active testing as a part of an IETF > bakeathon for NFSv4. During the week I had a NFSv4 client > crash. On the surface, it is straightforward, in that it called > ncl_doio_directwrite() and the field called b_caller1 was NULL. > > Now, here's the weird part... > ncl_doio_directwrite() should never be called because B_DIRECT > should never be set. (The only place B_DIRECT gets set in the code > is never currently executed.) Do you mean the place in nfs_directio_write()? And the fact that IO_SYNC is always set. > > I have a patch that clears out the "never to be executed" code and > this seems to avoid the patch, since with the patch, ncl_doio_directwrite() > no longer exists. > > What I cannot figure out is how B_DIRECT got set? > I can note that UFS was under heavy load when the client crashed, > but I cannot see how a UFS "struct buf" would become a NFS "struct buf" > without b_flags being set to 0. There are also vfs_bio_brelse()/vfs_bio_setflags() functions which can set B_DIRECT. On the other hand, they are not used by nfs client. What was the overall state of the buffer with the B_DIRECT flag? Which vnode it was assigned to?
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