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author | Jeff Layton <jeff.layton@primarydata.com> | 2019-08-18 14:18:57 -0400 |
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committer | J. Bruce Fields <bfields@redhat.com> | 2019-08-19 11:09:10 -0400 |
commit | 7775ec57f4c71309109f9e98cf8854a2ca8c9df1 (patch) | |
tree | a5c20ba739bdc4692bb7b2ae399d249eea9d1c5e /fs/nfsd | |
parent | 501cb1849f865960501d19d54e6a5af306f9b6fd (diff) | |
download | linux-7775ec57f4c71309109f9e98cf8854a2ca8c9df1.tar.gz linux-7775ec57f4c71309109f9e98cf8854a2ca8c9df1.tar.bz2 linux-7775ec57f4c71309109f9e98cf8854a2ca8c9df1.zip |
nfsd: close cached files prior to a REMOVE or RENAME that would replace target
It's not uncommon for some workloads to do a bunch of I/O to a file and
delete it just afterward. If knfsd has a cached open file however, then
the file may still be open when the dentry is unlinked. If the
underlying filesystem is nfs, then that could trigger it to do a
sillyrename.
On a REMOVE or RENAME scan the nfsd_file cache for open files that
correspond to the inode, and proactively unhash and put their
references. This should prevent any delete-on-last-close activity from
occurring, solely due to knfsd's open file cache.
This must be done synchronously though so we use the variants that call
flush_delayed_fput. There are deadlock possibilities if you call
flush_delayed_fput while holding locks, however. In the case of
nfsd_rename, we don't even do the lookups of the dentries to be renamed
until we've locked for rename.
Once we've figured out what the target dentry is for a rename, check to
see whether there are cached open files associated with it. If there
are, then unwind all of the locking, close them all, and then reattempt
the rename.
Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Diffstat (limited to 'fs/nfsd')
-rw-r--r-- | fs/nfsd/vfs.c | 62 |
1 files changed, 53 insertions, 9 deletions
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index 8e2c8f36eba3..84e87772c2b8 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -1590,6 +1590,26 @@ out_nfserr: goto out_unlock; } +static void +nfsd_close_cached_files(struct dentry *dentry) +{ + struct inode *inode = d_inode(dentry); + + if (inode && S_ISREG(inode->i_mode)) + nfsd_file_close_inode_sync(inode); +} + +static bool +nfsd_has_cached_files(struct dentry *dentry) +{ + bool ret = false; + struct inode *inode = d_inode(dentry); + + if (inode && S_ISREG(inode->i_mode)) + ret = nfsd_file_is_cached(inode); + return ret; +} + /* * Rename a file * N.B. After this call _both_ ffhp and tfhp need an fh_put @@ -1602,6 +1622,7 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen, struct inode *fdir, *tdir; __be32 err; int host_err; + bool has_cached = false; err = fh_verify(rqstp, ffhp, S_IFDIR, NFSD_MAY_REMOVE); if (err) @@ -1620,6 +1641,7 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen, if (!flen || isdotent(fname, flen) || !tlen || isdotent(tname, tlen)) goto out; +retry: host_err = fh_want_write(ffhp); if (host_err) { err = nfserrno(host_err); @@ -1659,11 +1681,16 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen, if (ffhp->fh_export->ex_path.dentry != tfhp->fh_export->ex_path.dentry) goto out_dput_new; - host_err = vfs_rename(fdir, odentry, tdir, ndentry, NULL, 0); - if (!host_err) { - host_err = commit_metadata(tfhp); - if (!host_err) - host_err = commit_metadata(ffhp); + if (nfsd_has_cached_files(ndentry)) { + has_cached = true; + goto out_dput_old; + } else { + host_err = vfs_rename(fdir, odentry, tdir, ndentry, NULL, 0); + if (!host_err) { + host_err = commit_metadata(tfhp); + if (!host_err) + host_err = commit_metadata(ffhp); + } } out_dput_new: dput(ndentry); @@ -1676,12 +1703,26 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen, * as that would do the wrong thing if the two directories * were the same, so again we do it by hand. */ - fill_post_wcc(ffhp); - fill_post_wcc(tfhp); + if (!has_cached) { + fill_post_wcc(ffhp); + fill_post_wcc(tfhp); + } unlock_rename(tdentry, fdentry); ffhp->fh_locked = tfhp->fh_locked = false; fh_drop_write(ffhp); + /* + * If the target dentry has cached open files, then we need to try to + * close them prior to doing the rename. Flushing delayed fput + * shouldn't be done with locks held however, so we delay it until this + * point and then reattempt the whole shebang. + */ + if (has_cached) { + has_cached = false; + nfsd_close_cached_files(ndentry); + dput(ndentry); + goto retry; + } out: return err; } @@ -1728,10 +1769,13 @@ nfsd_unlink(struct svc_rqst *rqstp, struct svc_fh *fhp, int type, if (!type) type = d_inode(rdentry)->i_mode & S_IFMT; - if (type != S_IFDIR) + if (type != S_IFDIR) { + nfsd_close_cached_files(rdentry); host_err = vfs_unlink(dirp, rdentry, NULL); - else + } else { host_err = vfs_rmdir(dirp, rdentry); + } + if (!host_err) host_err = commit_metadata(fhp); dput(rdentry); |