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Fix readdirplus in the experimental NFS client so that it

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skips over ".." to avoid a LOR race with nfs_lookup(). This
fix is analagous to r138256 in the regular NFS client.

MFC after:	2 weeks
This commit is contained in:
Rick Macklem 2011-04-17 02:44:51 +00:00
parent 4b3a38ecdf
commit f5613c1d97
1 changed files with 22 additions and 1 deletions
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23
sys/fs/nfsclient/nfs_clrpcops.c
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@ -2942,7 +2942,7 @@ nfsrpc_readdirplus(vnode_t vp, struct uio *uiop, nfsuint64 *cookiep,
nfsquad_t cookie, ncookie;
int error = 0, tlen, more_dirs = 1, blksiz = 0, bigenough = 1;
int attrflag, tryformoredirs = 1, eof = 0, gotmnton = 0;
int unlocknewvp = 0;
int isdotdot = 0, unlocknewvp = 0;
long dotfileid, dotdotfileid = 0, fileno = 0;
char *cp;
nfsattrbit_t attrbits, dattrbits;
@ -3192,6 +3192,11 @@ nfsrpc_readdirplus(vnode_t vp, struct uio *uiop, nfsuint64 *cookiep,
*cp = '\0';
cp += tlen; /* points to cookie storage */
tl2 = (u_int32_t *)cp;
if (len == 2 && cnp->cn_nameptr[0] == '.' &&
cnp->cn_nameptr[1] == '.')
isdotdot = 1;
else
isdotdot = 0;
uio_iov_base_add(uiop, (tlen + NFSX_HYPER));
uio_iov_len_add(uiop, -(tlen + NFSX_HYPER));
uio_uio_resid_add(uiop, -(tlen + NFSX_HYPER));
@ -3269,6 +3274,22 @@ nfsrpc_readdirplus(vnode_t vp, struct uio *uiop, nfsuint64 *cookiep,
unlocknewvp = 0;
FREE((caddr_t)nfhp, M_NFSFH);
np = dnp;
} else if (isdotdot != 0) {
/*
* Skip doing a nfscl_nget() call for "..".
* There's a race between acquiring the nfs
* node here and lookups that look for the
* directory being read (in the parent).
* It would try to get a lock on ".." here,
* owning the lock on the directory being
* read. Lookup will hold the lock on ".."
* and try to acquire the lock on the
* directory being read.
* If the directory is unlocked/relocked,
* then there is a LOR with the buflock
* vp is relocked.
*/
free(nfhp, M_NFSFH);
} else {
error = nfscl_nget(vnode_mount(vp), vp,
nfhp, cnp, p, &np, NULL, LK_EXCLUSIVE);