Commit a578a8ef authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Carlos Maiolino
Browse files

xfs: clean up the initial read logic in xfs_readsb 



The initial sb read is always for a device logical block size buffer.
The device logical block size is provided in the bt_logical_sectorsize in
struct buftarg, so use that instead of the confusingly named
xfs_getsize_buftarg buffer that reads it from the bdev.

Update the comments surrounding the code to better describe what is going
on.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDarrick J. Wong <djwong@kernel.org>
Signed-off-by: default avatarCarlos Maiolino <cem@kernel.org>
parent f2eb2796

fs/xfs/xfs_buf.h

+0 −1
Original line number Diff line number Diff line
@@ -375,7 +375,6 @@ extern void xfs_buftarg_wait(struct xfs_buftarg *); 
extern void xfs_buftarg_drain(struct xfs_buftarg *);

int xfs_configure_buftarg(struct xfs_buftarg *btp, unsigned int sectorsize);



#define xfs_getsize_buftarg(buftarg)	block_size((buftarg)->bt_bdev)

#define xfs_readonly_buftarg(buftarg)	bdev_read_only((buftarg)->bt_bdev)



int xfs_buf_reverify(struct xfs_buf *bp, const struct xfs_buf_ops *ops);

fs/xfs/xfs_mount.c

+11 −10
Original line number Diff line number Diff line
@@ -171,19 +171,16 @@ xfs_readsb( 
	ASSERT(mp->m_ddev_targp != NULL);



	/*

	 * For the initial read, we must guess at the sector

	 * size based on the block device.  It's enough to

	 * get the sb_sectsize out of the superblock and

	 * then reread with the proper length.

	 * We don't verify it yet, because it may not be complete.

	 * In the first pass, use the device sector size to just read enough

	 * of the superblock to extract the XFS sector size.

	 *

	 * The device sector size must be smaller than or equal to the XFS

	 * sector size and thus we can always read the superblock.  Once we know

	 * the XFS sector size, re-read it and run the buffer verifier.

	 */

	sector_size = xfs_getsize_buftarg(mp->m_ddev_targp);

	sector_size = mp->m_ddev_targp->bt_logical_sectorsize;

	buf_ops = NULL;



	/*

	 * Allocate a (locked) buffer to hold the superblock. This will be kept

	 * around at all times to optimize access to the superblock.

	 */

reread:

	error = xfs_buf_read_uncached(mp->m_ddev_targp, XFS_SB_DADDR,

				      BTOBB(sector_size), &bp, buf_ops);
@@ -247,6 +244,10 @@ xfs_readsb( 
	/* no need to be quiet anymore, so reset the buf ops */

	bp->b_ops = &xfs_sb_buf_ops;



	/*

	 * Keep a pointer of the sb buffer around instead of caching it in the

	 * buffer cache because we access it frequently.

	 */

	mp->m_sb_bp = bp;

	xfs_buf_unlock(bp);

	return 0;