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-rw-r--r--fs/gfs2/ops_address.c74
1 files changed, 45 insertions, 29 deletions
diff --git a/fs/gfs2/ops_address.c b/fs/gfs2/ops_address.c
index d8d69a7..0118aa4 100644
--- a/fs/gfs2/ops_address.c
+++ b/fs/gfs2/ops_address.c
@@ -594,6 +594,36 @@ static void gfs2_invalidatepage(struct page *page, unsigned long offset)
return;
}
+/**
+ * gfs2_ok_for_dio - check that dio is valid on this file
+ * @ip: The inode
+ * @rw: READ or WRITE
+ * @offset: The offset at which we are reading or writing
+ *
+ * Returns: 0 (to ignore the i/o request and thus fall back to buffered i/o)
+ * 1 (to accept the i/o request)
+ */
+static int gfs2_ok_for_dio(struct gfs2_inode *ip, int rw, loff_t offset)
+{
+ /*
+ * Should we return an error here? I can't see that O_DIRECT for
+ * a journaled file makes any sense. For now we'll silently fall
+ * back to buffered I/O, likewise we do the same for stuffed
+ * files since they are (a) small and (b) unaligned.
+ */
+ if (gfs2_is_jdata(ip))
+ return 0;
+
+ if (gfs2_is_stuffed(ip))
+ return 0;
+
+ if (offset > i_size_read(&ip->i_inode))
+ return 0;
+ return 1;
+}
+
+
+
static ssize_t gfs2_direct_IO(int rw, struct kiocb *iocb,
const struct iovec *iov, loff_t offset,
unsigned long nr_segs)
@@ -604,42 +634,28 @@ static ssize_t gfs2_direct_IO(int rw, struct kiocb *iocb,
struct gfs2_holder gh;
int rv;
- if (rw == READ)
- mutex_lock(&inode->i_mutex);
/*
- * Shared lock, even if its a write, since we do no allocation
- * on this path. All we need change is atime.
+ * Deferred lock, even if its a write, since we do no allocation
+ * on this path. All we need change is atime, and this lock mode
+ * ensures that other nodes have flushed their buffered read caches
+ * (i.e. their page cache entries for this inode). We do not,
+ * unfortunately have the option of only flushing a range like
+ * the VFS does.
*/
- gfs2_holder_init(ip->i_gl, LM_ST_SHARED, GL_ATIME, &gh);
+ gfs2_holder_init(ip->i_gl, LM_ST_DEFERRED, GL_ATIME, &gh);
rv = gfs2_glock_nq_atime(&gh);
if (rv)
- goto out;
-
- if (offset > i_size_read(inode))
- goto out;
-
- /*
- * Should we return an error here? I can't see that O_DIRECT for
- * a journaled file makes any sense. For now we'll silently fall
- * back to buffered I/O, likewise we do the same for stuffed
- * files since they are (a) small and (b) unaligned.
- */
- if (gfs2_is_jdata(ip))
- goto out;
-
- if (gfs2_is_stuffed(ip))
- goto out;
-
- rv = blockdev_direct_IO_own_locking(rw, iocb, inode,
- inode->i_sb->s_bdev,
- iov, offset, nr_segs,
- gfs2_get_block_direct, NULL);
+ return rv;
+ rv = gfs2_ok_for_dio(ip, rw, offset);
+ if (rv != 1)
+ goto out; /* dio not valid, fall back to buffered i/o */
+
+ rv = blockdev_direct_IO_no_locking(rw, iocb, inode, inode->i_sb->s_bdev,
+ iov, offset, nr_segs,
+ gfs2_get_block_direct, NULL);
out:
gfs2_glock_dq_m(1, &gh);
gfs2_holder_uninit(&gh);
- if (rw == READ)
- mutex_unlock(&inode->i_mutex);
-
return rv;
}