From 0a2bb03fe20f81dc4cac96d7fe0e4194ae6efffd Mon Sep 17 00:00:00 2001
From: André Fabian Silva Delgado <emulatorman@parabola.nu>
Date: Thu, 13 Aug 2015 01:32:17 -0300
Subject: Linux-libre 4.1.5-gnu
---
fs/xfs/libxfs/xfs_attr_remote.c | 44 +++++++++++++++++++++++++++++++----------
fs/xfs/xfs_log_recover.c | 11 ++++++++---
2 files changed, 42 insertions(+), 13 deletions(-)
(limited to 'fs/xfs')
diff --git a/fs/xfs/libxfs/xfs_attr_remote.c b/fs/xfs/libxfs/xfs_attr_remote.c
index 20de88d1b..dd714037c 100644
--- a/fs/xfs/libxfs/xfs_attr_remote.c
+++ b/fs/xfs/libxfs/xfs_attr_remote.c
@@ -159,11 +159,10 @@ xfs_attr3_rmt_write_verify(
struct xfs_buf *bp)
{
struct xfs_mount *mp = bp->b_target->bt_mount;
- struct xfs_buf_log_item *bip = bp->b_fspriv;
+ int blksize = mp->m_attr_geo->blksize;
char *ptr;
int len;
xfs_daddr_t bno;
- int blksize = mp->m_attr_geo->blksize;
/* no verification of non-crc buffers */
if (!xfs_sb_version_hascrc(&mp->m_sb))
@@ -175,16 +174,22 @@ xfs_attr3_rmt_write_verify(
ASSERT(len >= blksize);
while (len > 0) {
+ struct xfs_attr3_rmt_hdr *rmt = (struct xfs_attr3_rmt_hdr *)ptr;
+
if (!xfs_attr3_rmt_verify(mp, ptr, blksize, bno)) {
xfs_buf_ioerror(bp, -EFSCORRUPTED);
xfs_verifier_error(bp);
return;
}
- if (bip) {
- struct xfs_attr3_rmt_hdr *rmt;
- rmt = (struct xfs_attr3_rmt_hdr *)ptr;
- rmt->rm_lsn = cpu_to_be64(bip->bli_item.li_lsn);
+ /*
+ * Ensure we aren't writing bogus LSNs to disk. See
+ * xfs_attr3_rmt_hdr_set() for the explanation.
+ */
+ if (rmt->rm_lsn != cpu_to_be64(NULLCOMMITLSN)) {
+ xfs_buf_ioerror(bp, -EFSCORRUPTED);
+ xfs_verifier_error(bp);
+ return;
}
xfs_update_cksum(ptr, blksize, XFS_ATTR3_RMT_CRC_OFF);
@@ -221,6 +226,18 @@ xfs_attr3_rmt_hdr_set(
rmt->rm_owner = cpu_to_be64(ino);
rmt->rm_blkno = cpu_to_be64(bno);
+ /*
+ * Remote attribute blocks are written synchronously, so we don't
+ * have an LSN that we can stamp in them that makes any sense to log
+ * recovery. To ensure that log recovery handles overwrites of these
+ * blocks sanely (i.e. once they've been freed and reallocated as some
+ * other type of metadata) we need to ensure that the LSN has a value
+ * that tells log recovery to ignore the LSN and overwrite the buffer
+ * with whatever is in it's log. To do this, we use the magic
+ * NULLCOMMITLSN to indicate that the LSN is invalid.
+ */
+ rmt->rm_lsn = cpu_to_be64(NULLCOMMITLSN);
+
return sizeof(struct xfs_attr3_rmt_hdr);
}
@@ -434,14 +451,21 @@ xfs_attr_rmtval_set(
/*
* Allocate a single extent, up to the size of the value.
+ *
+ * Note that we have to consider this a data allocation as we
+ * write the remote attribute without logging the contents.
+ * Hence we must ensure that we aren't using blocks that are on
+ * the busy list so that we don't overwrite blocks which have
+ * recently been freed but their transactions are not yet
+ * committed to disk. If we overwrite the contents of a busy
+ * extent and then crash then the block may not contain the
+ * correct metadata after log recovery occurs.
*/
xfs_bmap_init(args->flist, args->firstblock);
nmap = 1;
error = xfs_bmapi_write(args->trans, dp, (xfs_fileoff_t)lblkno,
- blkcnt,
- XFS_BMAPI_ATTRFORK | XFS_BMAPI_METADATA,
- args->firstblock, args->total, &map, &nmap,
- args->flist);
+ blkcnt, XFS_BMAPI_ATTRFORK, args->firstblock,
+ args->total, &map, &nmap, args->flist);
if (!error) {
error = xfs_bmap_finish(&args->trans, args->flist,
&committed);
diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index 4f5784f85..a5d03396d 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -1887,9 +1887,14 @@ xlog_recover_get_buf_lsn(
uuid = &((struct xfs_dir3_blk_hdr *)blk)->uuid;
break;
case XFS_ATTR3_RMT_MAGIC:
- lsn = be64_to_cpu(((struct xfs_attr3_rmt_hdr *)blk)->rm_lsn);
- uuid = &((struct xfs_attr3_rmt_hdr *)blk)->rm_uuid;
- break;
+ /*
+ * Remote attr blocks are written synchronously, rather than
+ * being logged. That means they do not contain a valid LSN
+ * (i.e. transactionally ordered) in them, and hence any time we
+ * see a buffer to replay over the top of a remote attribute
+ * block we should simply do so.
+ */
+ goto recover_immediately;
case XFS_SB_MAGIC:
lsn = be64_to_cpu(((struct xfs_dsb *)blk)->sb_lsn);
uuid = &((struct xfs_dsb *)blk)->sb_uuid;
--
cgit v1.2.3-54-g00ecf