Messages in this thread | | | Date | Mon, 20 Jul 2020 16:53:40 +0200 | From | Dominique Martinet <> | Subject | Re: [RFC PATCH 1/2] vfs: pass file down when getattr to avoid losing info. |
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Jianyong Wu wrote on Mon, Jul 20, 2020: > Currently, getting attribute for a file represented by fd is always > by inode or path which may lead to bug for a certain network file system. > Adding file struct into struct kstat and assigning file for it in > vfs_statx_fd can avoid this issue. This change refers to struct istat. > > Signed-off-by: Jianyong Wu <jianyong.wu@arm.com> > --- > fs/stat.c | 1 + > include/linux/stat.h | 6 ++++++ > 2 files changed, 7 insertions(+) > > diff --git a/fs/stat.c b/fs/stat.c > index 44f8ad346db4..0dee5487f6d6 100644 > --- a/fs/stat.c > +++ b/fs/stat.c > @@ -147,6 +147,7 @@ int vfs_statx_fd(unsigned int fd, struct kstat *stat, > return -EINVAL; > > f = fdget_raw(fd); > + stat->filp = f.file; > if (f.file) { > error = vfs_getattr(&f.file->f_path, stat, > request_mask, query_flags); > diff --git a/include/linux/stat.h b/include/linux/stat.h > index 56614af83d4a..4755c528d49a 100644 > --- a/include/linux/stat.h > +++ b/include/linux/stat.h > @@ -48,6 +48,12 @@ struct kstat { > struct timespec64 btime; /* File creation time */ > u64 blocks; > u64 mnt_id; > + > + /* > + * Not an attribute, but an auxiliary info for filesystems wanting to > + * implement an fstat() like method. > + */ > + struct file *filp;
Just, no ; don't touch this, it isn't likely to get accepted ever. file operations should all have a filp around already, we need to fix this in our code.
(also missing quite a few Cc if you ever want to touch these bits, at least linux-fsdevel@)
FWIW the problem has been discussed a few times previously.
I'd appreciate if you could take over from Eric and Greg's old series that intended to fix that: https://lore.kernel.org/lkml/146659832556.15781.17414806975641516683.stgit@bahia.lan/
it introduced a race somewhere, but the idea looked good at the time so it's worth looking into.
-- Dominique
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