| Message ID | 155552788742.20411.8968554209133632884.stgit@magnolia (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | vfs: make immutable files actually immutable | expand |
On Wed, Apr 17, 2019 at 12:04:47PM -0700, Darrick J. Wong wrote: > From: Darrick J. Wong <darrick.wong@oracle.com> > > The chattr manpage has this to say about immutable files: > > "A file with the 'i' attribute cannot be modified: it cannot be deleted > or renamed, no link can be created to this file, most of the file's > metadata can not be modified, and the file can not be opened in write > mode." > > This means that we need to flush the page cache when setting the > immutable flag so that all mappings will become read-only again and > therefore programs cannot continue to write to writable mappings. > > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> > --- > fs/xfs/xfs_ioctl.c | 52 +++++++++++++++++++++++++++++++++++++++++++++------- > 1 file changed, 45 insertions(+), 7 deletions(-) > > > diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c > index 21d6f433c375..de35cf4469f6 100644 > --- a/fs/xfs/xfs_ioctl.c > +++ b/fs/xfs/xfs_ioctl.c > @@ -1009,6 +1009,31 @@ xfs_diflags_to_linux( > #endif > } > > +/* > + * Lock the inode against file io and page faults, then flush all dirty pages > + * and wait for writeback and direct IO operations to finish. Returns with > + * the relevant inode lock flags set in @join_flags. Caller is responsible for > + * unlocking even on error return. > + */ > +static int > +xfs_ioctl_setattr_flush( > + struct xfs_inode *ip, > + int *join_flags) > +{ > + struct inode *inode = VFS_I(ip); > + > + /* Already locked the inode from IO? Assume we're done. */ > + if (((*join_flags) & (XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL)) == > + (XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL)) > + return 0; > + Ok, so I take it this is because the xfs_setattr_path() can call down into here via dax_invalidate() and then subsequently via the immutable check. Instead of burying this down here, could we just check join_flags != 0 prior to the second setattr_flush() call? Otherwise this looks Ok to me. Brian > + /* Lock and flush all mappings and IO in preparation for flag change */ > + *join_flags = XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL; > + xfs_ilock(ip, *join_flags); > + inode_dio_wait(inode); > + return filemap_write_and_wait(inode->i_mapping); > +} > + > static int > xfs_ioctl_setattr_xflags( > struct xfs_trans *tp, > @@ -1103,25 +1128,22 @@ xfs_ioctl_setattr_dax_invalidate( > if (!(fa->fsx_xflags & FS_XFLAG_DAX) && !IS_DAX(inode)) > return 0; > > - if (S_ISDIR(inode->i_mode)) > + if (!S_ISREG(inode->i_mode)) > return 0; > > /* lock, flush and invalidate mapping in preparation for flag change */ > - xfs_ilock(ip, XFS_MMAPLOCK_EXCL | XFS_IOLOCK_EXCL); > - error = filemap_write_and_wait(inode->i_mapping); > + error = xfs_ioctl_setattr_flush(ip, join_flags); > if (error) > goto out_unlock; > error = invalidate_inode_pages2(inode->i_mapping); > if (error) > goto out_unlock; > - > - *join_flags = XFS_MMAPLOCK_EXCL | XFS_IOLOCK_EXCL; > return 0; > > out_unlock: > - xfs_iunlock(ip, XFS_MMAPLOCK_EXCL | XFS_IOLOCK_EXCL); > + xfs_iunlock(ip, *join_flags); > + *join_flags = 0; > return error; > - > } > > /* > @@ -1367,6 +1389,22 @@ xfs_ioctl_setattr( > if (code) > goto error_free_dquots; > > + /* > + * Wait for all pending directio and then flush all the dirty pages > + * for this file. The flush marks all the pages readonly, so any > + * subsequent attempt to write to the file (particularly mmap pages) > + * will come through the filesystem and fail. > + */ > + if (S_ISREG(VFS_I(ip)->i_mode) && !IS_IMMUTABLE(VFS_I(ip)) && > + (fa->fsx_xflags & FS_XFLAG_IMMUTABLE)) { > + code = xfs_ioctl_setattr_flush(ip, &join_flags); > + if (code) { > + xfs_iunlock(ip, join_flags); > + join_flags = 0; > + goto error_free_dquots; > + } > + } > + > tp = xfs_ioctl_setattr_get_trans(ip, join_flags); > if (IS_ERR(tp)) { > code = PTR_ERR(tp); >
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c index 21d6f433c375..de35cf4469f6 100644 --- a/fs/xfs/xfs_ioctl.c +++ b/fs/xfs/xfs_ioctl.c @@ -1009,6 +1009,31 @@ xfs_diflags_to_linux( #endif } +/* + * Lock the inode against file io and page faults, then flush all dirty pages + * and wait for writeback and direct IO operations to finish. Returns with + * the relevant inode lock flags set in @join_flags. Caller is responsible for + * unlocking even on error return. + */ +static int +xfs_ioctl_setattr_flush( + struct xfs_inode *ip, + int *join_flags) +{ + struct inode *inode = VFS_I(ip); + + /* Already locked the inode from IO? Assume we're done. */ + if (((*join_flags) & (XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL)) == + (XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL)) + return 0; + + /* Lock and flush all mappings and IO in preparation for flag change */ + *join_flags = XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL; + xfs_ilock(ip, *join_flags); + inode_dio_wait(inode); + return filemap_write_and_wait(inode->i_mapping); +} + static int xfs_ioctl_setattr_xflags( struct xfs_trans *tp, @@ -1103,25 +1128,22 @@ xfs_ioctl_setattr_dax_invalidate( if (!(fa->fsx_xflags & FS_XFLAG_DAX) && !IS_DAX(inode)) return 0; - if (S_ISDIR(inode->i_mode)) + if (!S_ISREG(inode->i_mode)) return 0; /* lock, flush and invalidate mapping in preparation for flag change */ - xfs_ilock(ip, XFS_MMAPLOCK_EXCL | XFS_IOLOCK_EXCL); - error = filemap_write_and_wait(inode->i_mapping); + error = xfs_ioctl_setattr_flush(ip, join_flags); if (error) goto out_unlock; error = invalidate_inode_pages2(inode->i_mapping); if (error) goto out_unlock; - - *join_flags = XFS_MMAPLOCK_EXCL | XFS_IOLOCK_EXCL; return 0; out_unlock: - xfs_iunlock(ip, XFS_MMAPLOCK_EXCL | XFS_IOLOCK_EXCL); + xfs_iunlock(ip, *join_flags); + *join_flags = 0; return error; - } /* @@ -1367,6 +1389,22 @@ xfs_ioctl_setattr( if (code) goto error_free_dquots; + /* + * Wait for all pending directio and then flush all the dirty pages + * for this file. The flush marks all the pages readonly, so any + * subsequent attempt to write to the file (particularly mmap pages) + * will come through the filesystem and fail. + */ + if (S_ISREG(VFS_I(ip)->i_mode) && !IS_IMMUTABLE(VFS_I(ip)) && + (fa->fsx_xflags & FS_XFLAG_IMMUTABLE)) { + code = xfs_ioctl_setattr_flush(ip, &join_flags); + if (code) { + xfs_iunlock(ip, join_flags); + join_flags = 0; + goto error_free_dquots; + } + } + tp = xfs_ioctl_setattr_get_trans(ip, join_flags); if (IS_ERR(tp)) { code = PTR_ERR(tp);