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authorNeilBrown <neilb@suse.de>2022-05-09 18:20:49 -0700
committerakpm <akpm@linux-foundation.org>2022-05-09 18:20:49 -0700
commita2ad63daa88b9d6846976fd2a0b5e4f5cfc58377 (patch)
treeb9f241f9b747df5b8604ec839e1de51fd67891b5 /fs/overlayfs/file.c
parent6341a446a0e66355d729b663d7c8ca28ad6d1442 (diff)
VFS: add FMODE_CAN_ODIRECT file flag
Currently various places test if direct IO is possible on a file by checking for the existence of the direct_IO address space operation. This is a poor choice, as the direct_IO operation may not be used - it is only used if the generic_file_*_iter functions are called for direct IO and some filesystems - particularly NFS - don't do this. Instead, introduce a new f_mode flag: FMODE_CAN_ODIRECT and change the various places to check this (avoiding pointer dereferences). do_dentry_open() will set this flag if ->direct_IO is present, so filesystems do not need to be changed. NFS *is* changed, to set the flag explicitly and discard the direct_IO entry in the address_space_operations for files. Other filesystems which currently use noop_direct_IO could usefully be changed to set this flag instead. Link: https://lkml.kernel.org/r/164859778128.29473.15189737957277399416.stgit@noble.brown Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: NeilBrown <neilb@suse.de> Tested-by: David Howells <dhowells@redhat.com> Tested-by: Geert Uytterhoeven <geert+renesas@glider.be> Cc: Hugh Dickins <hughd@google.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Trond Myklebust <trond.myklebust@hammerspace.com> Cc: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'fs/overlayfs/file.c')
-rw-r--r--fs/overlayfs/file.c13
1 files changed, 4 insertions, 9 deletions
diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
index fa125feed0ff..9d69b4dbb8c4 100644
--- a/fs/overlayfs/file.c
+++ b/fs/overlayfs/file.c
@@ -82,11 +82,8 @@ static int ovl_change_flags(struct file *file, unsigned int flags)
if (((flags ^ file->f_flags) & O_APPEND) && IS_APPEND(inode))
return -EPERM;
- if (flags & O_DIRECT) {
- if (!file->f_mapping->a_ops ||
- !file->f_mapping->a_ops->direct_IO)
- return -EINVAL;
- }
+ if ((flags & O_DIRECT) && !(file->f_mode & FMODE_CAN_ODIRECT))
+ return -EINVAL;
if (file->f_op->check_flags) {
err = file->f_op->check_flags(flags);
@@ -306,8 +303,7 @@ static ssize_t ovl_read_iter(struct kiocb *iocb, struct iov_iter *iter)
ret = -EINVAL;
if (iocb->ki_flags & IOCB_DIRECT &&
- (!real.file->f_mapping->a_ops ||
- !real.file->f_mapping->a_ops->direct_IO))
+ !(real.file->f_mode & FMODE_CAN_ODIRECT))
goto out_fdput;
old_cred = ovl_override_creds(file_inode(file)->i_sb);
@@ -367,8 +363,7 @@ static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter)
ret = -EINVAL;
if (iocb->ki_flags & IOCB_DIRECT &&
- (!real.file->f_mapping->a_ops ||
- !real.file->f_mapping->a_ops->direct_IO))
+ !(real.file->f_mode & FMODE_CAN_ODIRECT))
goto out_fdput;
if (!ovl_should_sync(OVL_FS(inode->i_sb)))