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gossipd: don't use O_APPEND on the gossip_store. 

We always know the length, so we don't need it.  It causes much extra work
when we want to delete a record, which I suspect may cause issues amongst
some users who've been seeing gossip_store corruption.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2019-07-30 10:40:09 +09:30 committed by Christian Decker
parent 4c9bfa351a
commit f57f068592
1 changed files with 12 additions and 24 deletions
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36
gossipd/gossip_store.c
View File

@ -66,15 +66,15 @@ static bool append_msg(int fd, const u8 *msg, u32 timestamp, u64 *len)
hdr.crc = cpu_to_be32(crc32c(timestamp, msg, msglen)); hdr.crc = cpu_to_be32(crc32c(timestamp, msg, msglen));
hdr.timestamp = cpu_to_be32(timestamp); hdr.timestamp = cpu_to_be32(timestamp);
if (len) /* Use pwritev so it will appear in store atomically */
*len += sizeof(hdr) + msglen;
/* Use writev so it will appear in store atomically */
iov[0].iov_base = &hdr; iov[0].iov_base = &hdr;
iov[0].iov_len = sizeof(hdr); iov[0].iov_len = sizeof(hdr);
iov[1].iov_base = (void *)msg; iov[1].iov_base = (void *)msg;
iov[1].iov_len = msglen; iov[1].iov_len = msglen;
return writev(fd, iov, ARRAY_SIZE(iov)) == sizeof(hdr) + msglen; if (pwritev(fd, iov, ARRAY_SIZE(iov), *len) != sizeof(hdr) + msglen)
return false;
*len += sizeof(hdr) + msglen;
return true;
} }
/* Read gossip store entries, copy non-deleted ones. This code is written /* Read gossip store entries, copy non-deleted ones. This code is written
@ -166,7 +166,7 @@ struct gossip_store *gossip_store_new(struct routing_state *rstate,
gs->count = gs->deleted = 0; gs->count = gs->deleted = 0;
gs->writable = true; gs->writable = true;
gossip_store_compact_offline(); gossip_store_compact_offline();
gs->fd = open(GOSSIP_STORE_FILENAME, O_RDWR|O_APPEND|O_CREAT, 0600); gs->fd = open(GOSSIP_STORE_FILENAME, O_RDWR|O_CREAT, 0600);
if (gs->fd < 0) if (gs->fd < 0)
status_failed(STATUS_FAIL_INTERNAL_ERROR, status_failed(STATUS_FAIL_INTERNAL_ERROR,
"Opening gossip_store store: %s", "Opening gossip_store store: %s",
@ -202,7 +202,8 @@ struct gossip_store *gossip_store_new(struct routing_state *rstate,
} }
/* Returns bytes transferred, or 0 on error */ /* Returns bytes transferred, or 0 on error */
static size_t transfer_store_msg(int from_fd, size_t from_off, int to_fd, static size_t transfer_store_msg(int from_fd, size_t from_off,
int to_fd, size_t to_off,
int *type) int *type)
{ {
struct gossip_hdr hdr; struct gossip_hdr hdr;
@ -237,7 +238,8 @@ static size_t transfer_store_msg(int from_fd, size_t from_off, int to_fd,
return 0; return 0;
} }
if (write(to_fd, msg, msglen + sizeof(hdr)) != msglen + sizeof(hdr)) { if (pwrite(to_fd, msg, msglen + sizeof(hdr), to_off)
!= msglen + sizeof(hdr)) {
status_broken("Failed writing to gossip store: %s", status_broken("Failed writing to gossip store: %s",
strerror(errno)); strerror(errno));
return 0; return 0;
@ -356,7 +358,7 @@ bool gossip_store_compact(struct gossip_store *gs)
} }
count++; count++;
wlen = transfer_store_msg(gs->fd, off, fd, &msgtype); wlen = transfer_store_msg(gs->fd, off, fd, len, &msgtype);
if (wlen == 0) if (wlen == 0)
goto unlink_disable; goto unlink_disable;
@ -477,7 +479,6 @@ u64 gossip_store_add_private_update(struct gossip_store *gs, const u8 *update)
static u32 delete_by_index(struct gossip_store *gs, u32 index, int type) static u32 delete_by_index(struct gossip_store *gs, u32 index, int type)
{ {
beint32_t belen; beint32_t belen;
int flags;
/* Should never get here during loading! */ /* Should never get here during loading! */
assert(gs->writable); assert(gs->writable);
@ -494,22 +495,10 @@ static u32 delete_by_index(struct gossip_store *gs, u32 index, int type)
assert((be32_to_cpu(belen) & GOSSIP_STORE_LEN_DELETED_BIT) == 0); assert((be32_to_cpu(belen) & GOSSIP_STORE_LEN_DELETED_BIT) == 0);
belen |= cpu_to_be32(GOSSIP_STORE_LEN_DELETED_BIT); belen |= cpu_to_be32(GOSSIP_STORE_LEN_DELETED_BIT);
/* From man pwrite(2):
*
* BUGS
* POSIX requires that opening a file with the O_APPEND flag should
* have no effect on the location at which pwrite() writes data.
* However, on Linux, if a file is opened with O_APPEND, pwrite()
* appends data to the end of the file, regardless of the value of
* offset.
*/
flags = fcntl(gs->fd, F_GETFL);
fcntl(gs->fd, F_SETFL, flags & ~O_APPEND);
if (pwrite(gs->fd, &belen, sizeof(belen), index) != sizeof(belen)) if (pwrite(gs->fd, &belen, sizeof(belen), index) != sizeof(belen))
status_failed(STATUS_FAIL_INTERNAL_ERROR, status_failed(STATUS_FAIL_INTERNAL_ERROR,
"Failed writing len to delete @%u: %s", "Failed writing len to delete @%u: %s",
index, strerror(errno)); index, strerror(errno));
fcntl(gs->fd, F_SETFL, flags);
gs->deleted++; gs->deleted++;
return index + sizeof(struct gossip_hdr) return index + sizeof(struct gossip_hdr)
@ -730,8 +719,7 @@ corrupt:
/* FIXME: Debug partial truncate case. */ /* FIXME: Debug partial truncate case. */
rename(GOSSIP_STORE_FILENAME, GOSSIP_STORE_FILENAME ".corrupt"); rename(GOSSIP_STORE_FILENAME, GOSSIP_STORE_FILENAME ".corrupt");
close(gs->fd); close(gs->fd);
gs->fd = open(GOSSIP_STORE_FILENAME, gs->fd = open(GOSSIP_STORE_FILENAME, O_RDWR|O_TRUNC|O_CREAT, 0600);
O_RDWR|O_APPEND|O_TRUNC|O_CREAT, 0600);
if (gs->fd < 0 || !write_all(gs->fd, &gs->version, sizeof(gs->version))) if (gs->fd < 0 || !write_all(gs->fd, &gs->version, sizeof(gs->version)))
status_failed(STATUS_FAIL_INTERNAL_ERROR, status_failed(STATUS_FAIL_INTERNAL_ERROR,
"Truncating new store file: %s", strerror(errno)); "Truncating new store file: %s", strerror(errno));