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authorToshi Kani <toshi.kani@hpe.com>2016-05-10 19:23:53 +0300
committerVishal Verma <vishal.l.verma@intel.com>2016-05-17 09:44:11 +0300
commit2d96afc8f70ef86c66a0b5d80c24a27d6dd13df3 (patch)
tree094e60ebc2d1ecd365c8d2e38a1502d0e6c36999 /fs/block_dev.c
parent2af3a8159cd204fc8437ed2f75863f0fb930f0d0 (diff)
downloadlinux-2d96afc8f70ef86c66a0b5d80c24a27d6dd13df3.tar.xz
block: Add bdev_dax_supported() for dax mount checks
DAX imposes additional requirements to a device. Add bdev_dax_supported() which performs all the precondition checks necessary for filesystem to mount the device with dax option. Also add a new check to verify if a partition is aligned by 4KB. When a partition is unaligned, any dax read/write access fails, except for metadata update. Signed-off-by: Toshi Kani <toshi.kani@hpe.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Jens Axboe <axboe@fb.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: Jan Kara <jack@suse.cz> Cc: Dave Chinner <david@fromorbit.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Boaz Harrosh <boaz@plexistor.com> Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
Diffstat (limited to 'fs/block_dev.c')
-rw-r--r--fs/block_dev.c45
1 files changed, 45 insertions, 0 deletions
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 91e0ec0233c0..518cde62c01c 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -509,6 +509,51 @@ long bdev_direct_access(struct block_device *bdev, struct blk_dax_ctl *dax)
}
EXPORT_SYMBOL_GPL(bdev_direct_access);
+/**
+ * bdev_dax_supported() - Check if the device supports dax for filesystem
+ * @sb: The superblock of the device
+ * @blocksize: The block size of the device
+ *
+ * This is a library function for filesystems to check if the block device
+ * can be mounted with dax option.
+ *
+ * Return: negative errno if unsupported, 0 if supported.
+ */
+int bdev_dax_supported(struct super_block *sb, int blocksize)
+{
+ struct blk_dax_ctl dax = {
+ .sector = 0,
+ .size = PAGE_SIZE,
+ };
+ int err;
+
+ if (blocksize != PAGE_SIZE) {
+ vfs_msg(sb, KERN_ERR, "error: unsupported blocksize for dax");
+ return -EINVAL;
+ }
+
+ err = bdev_direct_access(sb->s_bdev, &dax);
+ if (err < 0) {
+ switch (err) {
+ case -EOPNOTSUPP:
+ vfs_msg(sb, KERN_ERR,
+ "error: device does not support dax");
+ break;
+ case -EINVAL:
+ vfs_msg(sb, KERN_ERR,
+ "error: unaligned partition for dax");
+ break;
+ default:
+ vfs_msg(sb, KERN_ERR,
+ "error: dax access failed (%d)", err);
+ }
+ return err;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(bdev_dax_supported);
+
/*
* pseudo-fs
*/