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| author | NeilBrown <neilb@suse.de> | 2022-05-10 04:20:49 +0300 |
|---|---|---|
| committer | akpm <akpm@linux-foundation.org> | 2022-05-10 04:20:49 +0300 |
| commit | a2ad63daa88b9d6846976fd2a0b5e4f5cfc58377 (patch) | |
| tree | b9f241f9b747df5b8604ec839e1de51fd67891b5 /fs/open.c | |
| parent | 6341a446a0e66355d729b663d7c8ca28ad6d1442 (diff) | |
| download | linux-a2ad63daa88b9d6846976fd2a0b5e4f5cfc58377.tar.xz | |
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/open.c')
| -rw-r--r-- | fs/open.c | 9 |
1 files changed, 4 insertions, 5 deletions
diff --git a/fs/open.c b/fs/open.c index 1315253e0247..7b50d7a2f51d 100644 --- a/fs/open.c +++ b/fs/open.c @@ -834,16 +834,15 @@ static int do_dentry_open(struct file *f, if ((f->f_mode & FMODE_WRITE) && likely(f->f_op->write || f->f_op->write_iter)) f->f_mode |= FMODE_CAN_WRITE; + if (f->f_mapping->a_ops && f->f_mapping->a_ops->direct_IO) + f->f_mode |= FMODE_CAN_ODIRECT; f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC); file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping); - /* NB: we're sure to have correct a_ops only after f_op->open */ - if (f->f_flags & O_DIRECT) { - if (!f->f_mapping->a_ops || !f->f_mapping->a_ops->direct_IO) - return -EINVAL; - } + if ((f->f_flags & O_DIRECT) && !(f->f_mode & FMODE_CAN_ODIRECT)) + return -EINVAL; /* * XXX: Huge page cache doesn't support writing yet. Drop all page |