[PATCH 1/8] xfs: hide log iovec alignment constraints

Dave Chinner
2022-04-27T02:23:07Z

From: Dave Chinner <dchinner@redhat.com>

Callers currently have to round out the size of buffers to match the
aligment constraints of log iovecs and xlog_write(). They should not
need to know this detail, so introduce a new function to calculate
the iovec length (for use in ->iop_size implementations). Also
modify xlog_finish_iovec() to round up the length to the correct
alignment so the callers don't need to do this, either.

Convert the only user - inode forks - of this alignment rounding to
use the new interface.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
fs/xfs/libxfs/xfs_inode_fork.c | 12 +++---------
fs/xfs/xfs_inode_item.c | 25 +++++++------------------
fs/xfs/xfs_inode_item_recover.c | 4 ++--
fs/xfs/xfs_log.h | 23 +++++++++++++++++++++++
4 files changed, 35 insertions(+), 29 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
index 9aee4a1e2fe9..1a4cdf550f6d 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.c
+++ b/fs/xfs/libxfs/xfs_inode_fork.c
@@ -36,7 +36,7 @@ xfs_init_local_fork(
int64_t size)
{
struct xfs_ifork *ifp = XFS_IFORK_PTR(ip, whichfork);
- int mem_size = size, real_size = 0;
+ int mem_size = size;
bool zero_terminate;

/*
@@ -50,8 +50,7 @@ xfs_init_local_fork(
mem_size++;

if (size) {
- real_size = roundup(mem_size, 4);
- ifp->if_u1.if_data = kmem_alloc(real_size, KM_NOFS);
+ ifp->if_u1.if_data = kmem_alloc(mem_size, KM_NOFS);
memcpy(ifp->if_u1.if_data, data, size);
if (zero_terminate)
ifp->if_u1.if_data[size] = '\0';
@@ -497,12 +496,7 @@ xfs_idata_realloc(
return;
}

- /*
- * For inline data, the underlying buffer must be a multiple of 4 bytes
- * in size so that it can be logged and stay on word boundaries.
- * We enforce that here.
- */
- ifp->if_u1.if_data = krealloc(ifp->if_u1.if_data, roundup(new_size, 4),
+ ifp->if_u1.if_data = krealloc(ifp->if_u1.if_data, new_size,
GFP_NOFS | __GFP_NOFAIL);
ifp->if_bytes = new_size;
}
diff --git a/fs/xfs/xfs_inode_item.c b/fs/xfs/xfs_inode_item.c
index 00733a18ccdc..721def0639fd 100644
--- a/fs/xfs/xfs_inode_item.c
+++ b/fs/xfs/xfs_inode_item.c
@@ -71,7 +71,7 @@ xfs_inode_item_data_fork_size(
case XFS_DINODE_FMT_LOCAL:
if ((iip->ili_fields & XFS_ILOG_DDATA) &&
ip->i_df.if_bytes > 0) {
- *nbytes += roundup(ip->i_df.if_bytes, 4);
+ *nbytes += xlog_calc_iovec_len(ip->i_df.if_bytes);
*nvecs += 1;
}
break;
@@ -112,7 +112,7 @@ xfs_inode_item_attr_fork_size(
case XFS_DINODE_FMT_LOCAL:
if ((iip->ili_fields & XFS_ILOG_ADATA) &&
ip->i_afp->if_bytes > 0) {
- *nbytes += roundup(ip->i_afp->if_bytes, 4);
+ *nbytes += xlog_calc_iovec_len(ip->i_afp->if_bytes);
*nvecs += 1;
}
break;
@@ -204,17 +204,12 @@ xfs_inode_item_format_data_fork(
~(XFS_ILOG_DEXT | XFS_ILOG_DBROOT | XFS_ILOG_DEV);
if ((iip->ili_fields & XFS_ILOG_DDATA) &&
ip->i_df.if_bytes > 0) {
- /*
- * Round i_bytes up to a word boundary.
- * The underlying memory is guaranteed
- * to be there by xfs_idata_realloc().
- */
- data_bytes = roundup(ip->i_df.if_bytes, 4);
ASSERT(ip->i_df.if_u1.if_data != NULL);
ASSERT(ip->i_disk_size > 0);
xlog_copy_iovec(lv, vecp, XLOG_REG_TYPE_ILOCAL,
- ip->i_df.if_u1.if_data, data_bytes);
- ilf->ilf_dsize = (unsigned)data_bytes;
+ ip->i_df.if_u1.if_data,
+ ip->i_df.if_bytes);
+ ilf->ilf_dsize = (unsigned)ip->i_df.if_bytes;
ilf->ilf_size++;
} else {
iip->ili_fields &= ~XFS_ILOG_DDATA;
@@ -288,17 +283,11 @@ xfs_inode_item_format_attr_fork(

if ((iip->ili_fields & XFS_ILOG_ADATA) &&
ip->i_afp->if_bytes > 0) {
- /*
- * Round i_bytes up to a word boundary.
- * The underlying memory is guaranteed
- * to be there by xfs_idata_realloc().
- */
- data_bytes = roundup(ip->i_afp->if_bytes, 4);
ASSERT(ip->i_afp->if_u1.if_data != NULL);
xlog_copy_iovec(lv, vecp, XLOG_REG_TYPE_IATTR_LOCAL,
ip->i_afp->if_u1.if_data,
- data_bytes);
- ilf->ilf_asize = (unsigned)data_bytes;
+ ip->i_afp->if_bytes);
+ ilf->ilf_asize = (unsigned)ip->i_afp->if_bytes;
ilf->ilf_size++;
} else {
iip->ili_fields &= ~XFS_ILOG_ADATA;
diff --git a/fs/xfs/xfs_inode_item_recover.c b/fs/xfs/xfs_inode_item_recover.c
index 6d44f5fd6d7e..d28ffaebd067 100644
--- a/fs/xfs/xfs_inode_item_recover.c
+++ b/fs/xfs/xfs_inode_item_recover.c
@@ -462,7 +462,7 @@ xlog_recover_inode_commit_pass2(
ASSERT(in_f->ilf_size <= 4);
ASSERT((in_f->ilf_size == 3) || (fields & XFS_ILOG_AFORK));
ASSERT(!(fields & XFS_ILOG_DFORK) ||
- (len == in_f->ilf_dsize));
+ (len == xlog_calc_iovec_len(in_f->ilf_dsize)));

switch (fields & XFS_ILOG_DFORK) {
case XFS_ILOG_DDATA:
@@ -497,7 +497,7 @@ xlog_recover_inode_commit_pass2(
}
len = item->ri_buf[attr_index].i_len;
src = item->ri_buf[attr_index].i_addr;
- ASSERT(len == in_f->ilf_asize);
+ ASSERT(len == xlog_calc_iovec_len(in_f->ilf_asize));

switch (in_f->ilf_fields & XFS_ILOG_AFORK) {
case XFS_ILOG_ADATA:
diff --git a/fs/xfs/xfs_log.h b/fs/xfs/xfs_log.h
index 8dafe8f771c7..d9aebca3f971 100644
--- a/fs/xfs/xfs_log.h
+++ b/fs/xfs/xfs_log.h
@@ -21,6 +21,17 @@ struct xfs_log_vec {

#define XFS_LOG_VEC_ORDERED (-1)

+/*
+ * Calculate the log iovec length for a given user buffer length. Intended to be
+ * used by ->iop_size implementations when sizing buffers of arbitrary
+ * alignments.
+ */
+static inline int
+xlog_calc_iovec_len(int len)
+{
+ return roundup(len, 4);
+}
+
void *xlog_prepare_iovec(struct xfs_log_vec *lv, struct xfs_log_iovec **vecp,
uint type);

@@ -29,6 +40,12 @@ xlog_finish_iovec(struct xfs_log_vec *lv, struct xfs_log_iovec *vec, int len)
{
struct xlog_op_header *oph = vec->i_addr;

+ /*
+ * Always round up the length to the correct alignment so callers don't
+ * need to know anything about this log vec layout requirement.
+ */
+ len = xlog_calc_iovec_len(len);
+
/* opheader tracks payload length, logvec tracks region length */
oph->oh_len = cpu_to_be32(len);

@@ -36,8 +53,14 @@ xlog_finish_iovec(struct xfs_log_vec *lv, struct xfs_log_iovec *vec, int len)
lv->lv_buf_len += len;
lv->lv_bytes += len;
vec->i_len = len;
+
+ /* Catch buffer overruns */
+ ASSERT((void *)lv->lv_buf + lv->lv_bytes <= (void *)lv + lv->lv_size);
}

+/*
+ * Copy the amount of data requested by the caller into a new log iovec.
+ */
static inline void *
xlog_copy_iovec(struct xfs_log_vec *lv, struct xfs_log_iovec **vecp,
uint type, void *data, int len)
--
2.35.1