From: Darrick J. Wong <djwong@xxxxxxxxxx>
Allow the buffer cache to target in-memory files by connecting it to
xfiles.
Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
---
libxfs/libxfs_io.h | 14 +++++++++++++-
libxfs/rdwr.c | 47 +++++++++++++++++++++++++++++++++++++++++++----
2 files changed, 56 insertions(+), 5 deletions(-)
diff --git a/libxfs/libxfs_io.h b/libxfs/libxfs_io.h
index 3fa9e75dcaa..c002ef058ec 100644
--- a/libxfs/libxfs_io.h
+++ b/libxfs/libxfs_io.h
@@ -24,7 +24,10 @@ struct xfs_buftarg {
struct xfs_mount *bt_mount;
pthread_mutex_t lock;
unsigned long writes_left;
- dev_t bt_bdev;
+ union {
+ struct xfile *bt_xfile;
+ dev_t bt_bdev;
+ };
unsigned int flags;
struct cache *bcache; /* global buffer cache */
};
@@ -37,6 +40,15 @@ struct xfs_buftarg {
#define XFS_BUFTARG_INJECT_WRITE_FAIL (1 << 2)
/* purge buffers when lookups find a size mismatch */
#define XFS_BUFTARG_MISCOMPARE_PURGE (1 << 3)
+/* use xfile for */
+#define XFS_BUFTARG_IN_MEMORY (1 << 4)
+
+static inline bool
+xfs_buftarg_in_memory(
+ struct xfs_buftarg *btp)
+{
+ return btp->flags & XFS_BUFTARG_IN_MEMORY;
+}
/* Simulate the system crashing after a certain number of writes. */
static inline void
diff --git a/libxfs/rdwr.c b/libxfs/rdwr.c
index 5d63ec4f6de..9d36698bb5c 100644
--- a/libxfs/rdwr.c
+++ b/libxfs/rdwr.c
@@ -18,7 +18,7 @@
#include "xfs_inode.h"
#include "xfs_trans.h"
#include "libfrog/platform.h"
-
+#include "libxfs/xfile.h"
#include "libxfs.h"
static void libxfs_brelse(struct cache_node *node);
@@ -68,6 +68,9 @@ libxfs_device_zero(struct xfs_buftarg *btp, xfs_daddr_t start, uint len)
char *z;
int error, fd;
+ if (btp->flags & XFS_BUFTARG_IN_MEMORY)
+ return -EOPNOTSUPP;
+
fd = libxfs_device_to_fd(btp->bt_bdev);
start_offset = LIBXFS_BBTOOFF64(start);
@@ -578,6 +581,31 @@ libxfs_balloc(
return &bp->b_node;
}
+static inline int
+libxfs_buf_ioapply_in_memory(
+ struct xfs_buf *bp,
+ bool is_write)
+{
+ struct xfile *xfile = bp->b_target->bt_xfile;
+ loff_t pos = BBTOB(xfs_buf_daddr(bp));
+ size_t size = BBTOB(bp->b_length);
+ int error;
+
+ if (bp->b_nmaps > 1) {
+ /* We don't need or support multi-map buffers. */
+ ASSERT(0);
+ error = -EIO;
+ } else if (is_write) {
+ error = xfile_obj_store(xfile, bp->b_addr, size, pos);
+ } else {
+ error = xfile_obj_load(xfile, bp->b_addr, size, pos);
+ }
+ if (error)
+ bp->b_error = error;
+ else if (!is_write)
+ bp->b_flags |= LIBXFS_B_UPTODATE;
+ return error;
+}
static int
__read_buf(int fd, void *buf, int len, off64_t offset, int flags)
@@ -602,12 +630,16 @@ int
libxfs_readbufr(struct xfs_buftarg *btp, xfs_daddr_t blkno, struct xfs_buf *bp,
int len, int flags)
{
- int fd = libxfs_device_to_fd(btp->bt_bdev);
+ int fd;
int bytes = BBTOB(len);
int error;
ASSERT(len <= bp->b_length);
+ if (bp->b_target->flags & XFS_BUFTARG_IN_MEMORY)
+ return libxfs_buf_ioapply_in_memory(bp, false);
+
+ fd = libxfs_device_to_fd(btp->bt_bdev);
error = __read_buf(fd, bp->b_addr, bytes, LIBXFS_BBTOOFF64(blkno), flags);
if (!error &&
bp->b_target->bt_bdev == btp->bt_bdev &&
@@ -640,6 +672,9 @@ libxfs_readbufr_map(struct xfs_buftarg *btp, struct xfs_buf *bp, int flags)
void *buf;
int i;
+ if (bp->b_target->flags & XFS_BUFTARG_IN_MEMORY)
+ return libxfs_buf_ioapply_in_memory(bp, false);
+
fd = libxfs_device_to_fd(btp->bt_bdev);
buf = bp->b_addr;
for (i = 0; i < bp->b_nmaps; i++) {
@@ -824,7 +859,7 @@ int
libxfs_bwrite(
struct xfs_buf *bp)
{
- int fd = libxfs_device_to_fd(bp->b_target->bt_bdev);
+ int fd;
/*
* we never write buffers that are marked stale. This indicates they
@@ -859,7 +894,10 @@ libxfs_bwrite(
}
}
- if (!(bp->b_flags & LIBXFS_B_DISCONTIG)) {
+ if (bp->b_target->flags & XFS_BUFTARG_IN_MEMORY) {
+ libxfs_buf_ioapply_in_memory(bp, true);
+ } else if (!(bp->b_flags & LIBXFS_B_DISCONTIG)) {
+ fd = libxfs_device_to_fd(bp->b_target->bt_bdev);
bp->b_error = __write_buf(fd, bp->b_addr, BBTOB(bp->b_length),
LIBXFS_BBTOOFF64(xfs_buf_daddr(bp)),
bp->b_flags);
@@ -867,6 +905,7 @@ libxfs_bwrite(
int i;
void *buf = bp->b_addr;
+ fd = libxfs_device_to_fd(bp->b_target->bt_bdev);
for (i = 0; i < bp->b_nmaps; i++) {
off64_t offset = LIBXFS_BBTOOFF64(bp->b_maps[i].bm_bn);
int len = BBTOB(bp->b_maps[i].bm_len);
