From: Christoph Hellwig <hch@xxxxxx>
Go through filesystem paths and return EAGAIN if there's an operation (like
metadata) that would cause blocking.
Signed-off-by: Milosz Tanski <milosz@xxxxxxxxx>
---
fs/cifs/file.c | 6 ++++++
fs/ocfs2/file.c | 6 ++++++
fs/pipe.c | 3 ++-
fs/read_write.c | 17 +++++++++++------
fs/xfs/xfs_file.c | 4 ++++
mm/shmem.c | 4 ++++
6 files changed, 33 insertions(+), 7 deletions(-)
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 7c018a1..e7169ba 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -3005,6 +3005,9 @@ ssize_t cifs_user_readv(struct kiocb *iocb, struct iov_iter *to)
struct cifs_readdata *rdata, *tmp;
struct list_head rdata_list;
+ if (iocb->ki_rwflags & RWF_NONBLOCK)
+ return -EAGAIN;
+
len = iov_iter_count(to);
if (!len)
return 0;
@@ -3123,6 +3126,9 @@ cifs_strict_readv(struct kiocb *iocb, struct iov_iter *to)
((cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NOPOSIXBRL) == 0))
return generic_file_read_iter(iocb, to);
+ if (iocb->ki_rwflags & RWF_NONBLOCK)
+ return -EAGAIN;
+
/*
* We need to hold the sem to be sure nobody modifies lock list
* with a brlock that prevents reading.
diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 2930e23..d96f60d 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -2473,6 +2473,12 @@ static ssize_t ocfs2_file_read_iter(struct kiocb *iocb,
filp->f_path.dentry->d_name.name,
to->nr_segs); /* GRRRRR */
+ /*
+ * No non-blocking reads for ocfs2 for now. Might be doable with
+ * non-blocking cluster lock helpers.
+ */
+ if (iocb->ki_rwflags & RWF_NONBLOCK)
+ return -EAGAIN;
if (!inode) {
ret = -EINVAL;
diff --git a/fs/pipe.c b/fs/pipe.c
index 21981e5..212bf68 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -302,7 +302,8 @@ pipe_read(struct kiocb *iocb, struct iov_iter *to)
*/
if (ret)
break;
- if (filp->f_flags & O_NONBLOCK) {
+ if ((filp->f_flags & O_NONBLOCK) ||
+ (iocb->ki_rwflags & RWF_NONBLOCK)) {
ret = -EAGAIN;
break;
}
diff --git a/fs/read_write.c b/fs/read_write.c
index 29b5823..a3efa95 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -833,14 +833,19 @@ static ssize_t do_readv_writev(int type, struct file *file,
file_start_write(file);
}
- if (iter_fn)
+ if (iter_fn) {
ret = do_iter_readv_writev(file, type, iov, nr_segs, tot_len,
pos, iter_fn, flags);
- else if (fnv)
- ret = do_sync_readv_writev(file, iov, nr_segs, tot_len,
- pos, fnv);
- else
- ret = do_loop_readv_writev(file, iov, nr_segs, pos, fn);
+ } else {
+ if (type == READ && (flags & RWF_NONBLOCK))
+ return -EAGAIN;
+
+ if (fnv)
+ ret = do_sync_readv_writev(file, iov, nr_segs, tot_len,
+ pos, fnv);
+ else
+ ret = do_loop_readv_writev(file, iov, nr_segs, pos, fn);
+ }
if (type != READ)
file_end_write(file);
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index de5368c..cf61271 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -246,6 +246,10 @@ xfs_file_read_iter(
XFS_STATS_INC(xs_read_calls);
+ /* XXX: need a non-blocking iolock helper, shouldn't be too hard */
+ if (iocb->ki_rwflags & RWF_NONBLOCK)
+ return -EAGAIN;
+
if (unlikely(file->f_flags & O_DIRECT))
ioflags |= XFS_IO_ISDIRECT;
if (file->f_mode & FMODE_NOCMTIME)
diff --git a/mm/shmem.c b/mm/shmem.c
index 0e5fb22..ca2cae2 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1531,6 +1531,10 @@ static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
ssize_t retval = 0;
loff_t *ppos = &iocb->ki_pos;
+ /* XXX: should be easily supportable */
+ if (iocb->ki_rwflags & RWF_NONBLOCK)
+ return -EAGAIN;
+
/*
* Might this read be for a stacking filesystem? Then when reading
* holes of a sparse file, we actually need to allocate those pages,
--
2.1.0
--
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