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SubjectRe: [PATCH 15/28] ovl: Open file with data except for the case of fsync
On Wed, May 30, 2018 at 05:12:16PM +0200, Miklos Szeredi wrote:
> >> From: Vivek Goyal <vgoyal@redhat.com>
> >>
> >> ovl_open() should open file which contains data and not open metacopy
> >> inode. With the introduction of metacopy inodes, with current
> >> implementaion we will end up opening metacopy inode as well.
> >>
> >> But there can be certain circumstances like ovl_fsync() where we want to
> >> allow opening a metacopy inode instead.
> >>
> >> Hence, change ovl_open_realfile() and add _ovl_open_real() and add extra
> >> parameter which specifies whether to allow opening metacopy inode or not.
> >> If this parameter is false, we look for data inode and open that.
> >>
> >> This should allow covering both the cases.
> >>
> >> Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
> >> Reviewed-by: Amir Goldstein <amir73il@gmail.com>
> >> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
> >> ---
> >> fs/overlayfs/file.c | 39 ++++++++++++++++++++++++++++++---------
> >> 1 file changed, 30 insertions(+), 9 deletions(-)
> >>
> >> diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
> >> index 266692ce9a9a..c7738ef492c8 100644
> >> --- a/fs/overlayfs/file.c
> >> +++ b/fs/overlayfs/file.c
> >> @@ -14,11 +14,20 @@
> >> #include <linux/uio.h>
> >> #include "overlayfs.h"
> >>
> >> -static struct file *ovl_open_realfile(const struct file *file)
> >> +static char ovl_whatisit(struct inode *inode, struct inode *realinode)
> >> +{
> >> + if (realinode != ovl_inode_upper(inode))
> >> + return 'l';
> >> + if (ovl_has_upperdata(inode))
> >> + return 'u';
> >> + else
> >> + return 'm';
> >> +}
> >> +
> >> +static struct file *ovl_open_realfile(const struct file *file,
> >> + struct inode *realinode)
> >> {
> >> struct inode *inode = file_inode(file);
> >> - struct inode *upperinode = ovl_inode_upper(inode);
> >> - struct inode *realinode = upperinode ?: ovl_inode_lower(inode);
> >> struct file *realfile;
> >> const struct cred *old_cred;
> >>
> >> @@ -28,7 +37,7 @@ static struct file *ovl_open_realfile(const struct file *file)
> >> revert_creds(old_cred);
> >>
> >> pr_debug("open(%p[%pD2/%c], 0%o) -> (%p, 0%o)\n",
> >> - file, file, upperinode ? 'u' : 'l', file->f_flags,
> >> + file, file, ovl_whatisit(inode, realinode), file->f_flags,
> >> realfile, IS_ERR(realfile) ? 0 : realfile->f_flags);
> >>
> >> return realfile;
> >> @@ -72,17 +81,24 @@ static int ovl_change_flags(struct file *file, unsigned int flags)
> >> return 0;
> >> }
> >>
> >> -static int ovl_real_fdget(const struct file *file, struct fd *real)
> >> +static int ovl_real_fdget_meta(const struct file *file, struct fd *real,
> >> + bool allow_meta)
> >> {
> >> struct inode *inode = file_inode(file);
> >> + struct inode *realinode;
> >>
> >> real->flags = 0;
> >> real->file = file->private_data;
> >>
> >> + if (allow_meta)
> >> + realinode = ovl_inode_real(inode);
> >> + else
> >> + realinode = ovl_inode_realdata(inode);
> >> +
> >> /* Has it been copied up since we'd opened it? */
> >> - if (unlikely(file_inode(real->file) != ovl_inode_real(inode))) {
> >> + if (unlikely(file_inode(real->file) != realinode)) {
> >> real->flags = FDPUT_FPUT;
> >> - real->file = ovl_open_realfile(file);
> >> + real->file = ovl_open_realfile(file, realinode);
> >>
> >> return PTR_ERR_OR_ZERO(real->file);
> >> }
> >> @@ -94,6 +110,11 @@ static int ovl_real_fdget(const struct file *file, struct fd *real)
> >> return 0;
> >> }
> >>
> >> +static int ovl_real_fdget(const struct file *file, struct fd *real)
> >> +{
> >> + return ovl_real_fdget_meta(file, real, false);
> >> +}
> >> +
> >> static int ovl_open(struct inode *inode, struct file *file)
> >> {
> >> struct dentry *dentry = file_dentry(file);
> >> @@ -107,7 +128,7 @@ static int ovl_open(struct inode *inode, struct file *file)
> >> /* No longer need these flags, so don't pass them on to underlying fs */
> >> file->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
> >>
> >> - realfile = ovl_open_realfile(file);
> >> + realfile = ovl_open_realfile(file, ovl_inode_real(file_inode(file)));
>
> That was meant to be
>
> + realfile = ovl_open_realfile(file, ovl_inode_realdata(file_inode(file)));
>
> Is that correct?

Yes, that's correct.

While we are at it, can we also update patch changelog. I see that
_ovl_open_real() is not there anymore.

Thanks
Vivek

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