diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2023-02-20 22:21:02 +0300 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2023-02-20 22:21:02 +0300 |
commit | de630176bdf885eed442902afe94eb60d8f5f826 (patch) | |
tree | c64fbe4878e5440830104bd572a53c055245b865 /fs/nfsd/nfsfh.c | |
parent | 575a7e0f812a4968ad1e0c00026692ede040e13f (diff) | |
parent | 58a033c9a3e003e048a0431a296e58c6b363b02b (diff) | |
download | linux-de630176bdf885eed442902afe94eb60d8f5f826.tar.xz |
Merge tag 'iversion-v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux
Pull i_version updates from Jeff Layton:
"This overhauls how we handle i_version queries from nfsd.
Instead of having special routines and grabbing the i_version field
directly out of the inode in some cases, we've moved most of the
handling into the various filesystems' getattr operations. As a bonus,
this makes ceph's change attribute usable by knfsd as well.
This should pave the way for future work to make this value queryable
by userland, and to make it more resilient against rolling back on a
crash"
* tag 'iversion-v6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux:
nfsd: remove fetch_iversion export operation
nfsd: use the getattr operation to fetch i_version
nfsd: move nfsd4_change_attribute to nfsfh.c
ceph: report the inode version in getattr if requested
nfs: report the inode version in getattr if requested
vfs: plumb i_version handling into struct kstat
fs: clarify when the i_version counter must be updated
fs: uninline inode_query_iversion
Diffstat (limited to 'fs/nfsd/nfsfh.c')
-rw-r--r-- | fs/nfsd/nfsfh.c | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/fs/nfsd/nfsfh.c b/fs/nfsd/nfsfh.c index 8c52b6c9d31a..76ea268dc420 100644 --- a/fs/nfsd/nfsfh.c +++ b/fs/nfsd/nfsfh.c @@ -628,6 +628,10 @@ void fh_fill_pre_attrs(struct svc_fh *fhp) stat.mtime = inode->i_mtime; stat.ctime = inode->i_ctime; stat.size = inode->i_size; + if (v4 && IS_I_VERSION(inode)) { + stat.change_cookie = inode_query_iversion(inode); + stat.result_mask |= STATX_CHANGE_COOKIE; + } } if (v4) fhp->fh_pre_change = nfsd4_change_attribute(&stat, inode); @@ -659,6 +663,10 @@ void fh_fill_post_attrs(struct svc_fh *fhp) if (err) { fhp->fh_post_saved = false; fhp->fh_post_attr.ctime = inode->i_ctime; + if (v4 && IS_I_VERSION(inode)) { + fhp->fh_post_attr.change_cookie = inode_query_iversion(inode); + fhp->fh_post_attr.result_mask |= STATX_CHANGE_COOKIE; + } } else fhp->fh_post_saved = true; if (v4) @@ -748,3 +756,37 @@ enum fsid_source fsid_source(const struct svc_fh *fhp) return FSIDSOURCE_UUID; return FSIDSOURCE_DEV; } + +/* + * We could use i_version alone as the change attribute. However, i_version + * can go backwards on a regular file after an unclean shutdown. On its own + * that doesn't necessarily cause a problem, but if i_version goes backwards + * and then is incremented again it could reuse a value that was previously + * used before boot, and a client who queried the two values might incorrectly + * assume nothing changed. + * + * By using both ctime and the i_version counter we guarantee that as long as + * time doesn't go backwards we never reuse an old value. If the filesystem + * advertises STATX_ATTR_CHANGE_MONOTONIC, then this mitigation is not + * needed. + * + * We only need to do this for regular files as well. For directories, we + * assume that the new change attr is always logged to stable storage in some + * fashion before the results can be seen. + */ +u64 nfsd4_change_attribute(struct kstat *stat, struct inode *inode) +{ + u64 chattr; + + if (stat->result_mask & STATX_CHANGE_COOKIE) { + chattr = stat->change_cookie; + if (S_ISREG(inode->i_mode) && + !(stat->attributes & STATX_ATTR_CHANGE_MONOTONIC)) { + chattr += (u64)stat->ctime.tv_sec << 30; + chattr += stat->ctime.tv_nsec; + } + } else { + chattr = time_to_chattr(&stat->ctime); + } + return chattr; +} |