From 75d0230314997b18946c96dc3d93c8d61cfdb9a5 Mon Sep 17 00:00:00 2001 From: Brian Foster Date: Wed, 6 Feb 2019 09:25:29 -0800 Subject: [PATCH] xfs: clarify documentation for the function to reverify buffers Improve the documentation around xfs_buf_ensure_ops, which is the function that is responsible for cleaning up the b_ops state of buffers that go through xrep_findroot_block but don't match anything. Rename the function to xfs_buf_reverify. [darrick: this started off as bfoster mods of a previous patch of mine, but the renaming part is now this separate patch.] Signed-off-by: Darrick J. Wong Reviewed-by: Darrick J. Wong Signed-off-by: Brian Foster --- fs/xfs/xfs_buf.c | 35 +++++++++++++++-------------------- fs/xfs/xfs_buf.h | 2 +- fs/xfs/xfs_trans_buf.c | 2 +- 3 files changed, 17 insertions(+), 22 deletions(-) diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c index 4f5f2ff3f70f..d29246ac3721 100644 --- a/fs/xfs/xfs_buf.c +++ b/fs/xfs/xfs_buf.c @@ -776,29 +776,24 @@ _xfs_buf_read( } /* - * Set buffer ops on an unchecked buffer and validate it, if possible. + * Reverify a buffer found in cache without an attached ->b_ops. * - * If the caller passed in an ops structure and the buffer doesn't have ops - * assigned, set the ops and use them to verify the contents. If the contents - * cannot be verified, we'll clear XBF_DONE. We assume the buffer has no - * recorded errors and is already in XBF_DONE state. + * If the caller passed an ops structure and the buffer doesn't have ops + * assigned, set the ops and use it to verify the contents. If verification + * fails, clear XBF_DONE. We assume the buffer has no recorded errors and is + * already in XBF_DONE state on entry. * - * Under normal operations, every in-core buffer must have buffer ops assigned - * to them when the buffer is read in from disk so that we can validate the - * metadata. - * - * However, there are two scenarios where one can encounter in-core buffers - * that don't have buffer ops. The first is during log recovery of buffers on - * a V4 filesystem, though these buffers are purged at the end of recovery. - * - * The other is online repair, which tries to match arbitrary metadata blocks - * with btree types in order to find the root. If online repair doesn't match - * the buffer with /any/ btree type, the buffer remains in memory in DONE state - * with no ops, and a subsequent read_buf call from elsewhere will not set the - * ops. This function helps us fix this situation. + * Under normal operations, every in-core buffer is verified on read I/O + * completion. There are two scenarios that can lead to in-core buffers without + * an assigned ->b_ops. The first is during log recovery of buffers on a V4 + * filesystem, though these buffers are purged at the end of recovery. The + * other is online repair, which intentionally reads with a NULL buffer ops to + * run several verifiers across an in-core buffer in order to establish buffer + * type. If repair can't establish that, the buffer will be left in memory + * with NULL buffer ops. */ int -xfs_buf_ensure_ops( +xfs_buf_reverify( struct xfs_buf *bp, const struct xfs_buf_ops *ops) { @@ -840,7 +835,7 @@ xfs_buf_read_map( return bp; } - xfs_buf_ensure_ops(bp, ops); + xfs_buf_reverify(bp, ops); if (flags & XBF_ASYNC) { /* diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h index b9f5511ea998..1c436a85b71d 100644 --- a/fs/xfs/xfs_buf.h +++ b/fs/xfs/xfs_buf.h @@ -385,6 +385,6 @@ extern int xfs_setsize_buftarg(xfs_buftarg_t *, unsigned int); #define xfs_getsize_buftarg(buftarg) block_size((buftarg)->bt_bdev) #define xfs_readonly_buftarg(buftarg) bdev_read_only((buftarg)->bt_bdev) -int xfs_buf_ensure_ops(struct xfs_buf *bp, const struct xfs_buf_ops *ops); +int xfs_buf_reverify(struct xfs_buf *bp, const struct xfs_buf_ops *ops); #endif /* __XFS_BUF_H__ */ diff --git a/fs/xfs/xfs_trans_buf.c b/fs/xfs/xfs_trans_buf.c index 629f1479c9d2..7d65ebf1e847 100644 --- a/fs/xfs/xfs_trans_buf.c +++ b/fs/xfs/xfs_trans_buf.c @@ -277,7 +277,7 @@ xfs_trans_read_buf_map( * release this buffer when it kills the tranaction. */ ASSERT(bp->b_ops != NULL); - error = xfs_buf_ensure_ops(bp, ops); + error = xfs_buf_reverify(bp, ops); if (error) { xfs_buf_ioerror_alert(bp, __func__);