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block/nfs: refuse readahead if cache.direct is on 

if we open a NFS export with disabled cache we should refuse
the readahead feature as it will cache data inside libnfs.

If a export was opened with readahead enabled it should
futher not be allowed to disable the cache while running.

Cc: qemu-stable@nongnu.org
Signed-off-by: Peter Lieven <pl@kamp.de>
Reviewed-by: Jeff Cody <jcody@redhat.com>
Message-id: 1463662083-20814-2-git-send-email-pl@kamp.de
Signed-off-by: Jeff Cody <jcody@redhat.com>
This commit is contained in:
Peter Lieven 2016-05-19 14:48:02 +02:00 committed by Jeff Cody
parent 947eb2030e
commit 38f8d5e025
1 changed files with 16 additions and 4 deletions
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20
block/nfs.c
View File

@ -1,7 +1,7 @@
/* /*
* QEMU Block driver for native access to files on NFS shares * QEMU Block driver for native access to files on NFS shares
* *
* Copyright (c) 2014 Peter Lieven <pl@kamp.de> * Copyright (c) 2014-2016 Peter Lieven <pl@kamp.de>
* *
* Permission is hereby granted, free of charge, to any person obtaining a copy * Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal * of this software and associated documentation files (the "Software"), to deal
@ -47,6 +47,7 @@ typedef struct NFSClient {
bool has_zero_init; bool has_zero_init;
AioContext *aio_context; AioContext *aio_context;
blkcnt_t st_blocks; blkcnt_t st_blocks;
bool cache_used;
} NFSClient; } NFSClient;
typedef struct NFSRPC { typedef struct NFSRPC {
@ -278,7 +279,7 @@ static void nfs_file_close(BlockDriverState *bs)
} }
static int64_t nfs_client_open(NFSClient *client, const char *filename, static int64_t nfs_client_open(NFSClient *client, const char *filename,
int flags, Error **errp) int flags, Error **errp, int open_flags)
{ {
int ret = -EINVAL, i; int ret = -EINVAL, i;
struct stat st; struct stat st;
@ -330,12 +331,18 @@ static int64_t nfs_client_open(NFSClient *client, const char *filename,
nfs_set_tcp_syncnt(client->context, val); nfs_set_tcp_syncnt(client->context, val);
#ifdef LIBNFS_FEATURE_READAHEAD #ifdef LIBNFS_FEATURE_READAHEAD
} else if (!strcmp(qp->p[i].name, "readahead")) { } else if (!strcmp(qp->p[i].name, "readahead")) {
if (open_flags & BDRV_O_NOCACHE) {
error_setg(errp, "Cannot enable NFS readahead "
"if cache.direct = on");
goto fail;
}
if (val > QEMU_NFS_MAX_READAHEAD_SIZE) { if (val > QEMU_NFS_MAX_READAHEAD_SIZE) {
error_report("NFS Warning: Truncating NFS readahead" error_report("NFS Warning: Truncating NFS readahead"
" size to %d", QEMU_NFS_MAX_READAHEAD_SIZE); " size to %d", QEMU_NFS_MAX_READAHEAD_SIZE);
val = QEMU_NFS_MAX_READAHEAD_SIZE; val = QEMU_NFS_MAX_READAHEAD_SIZE;
} }
nfs_set_readahead(client->context, val); nfs_set_readahead(client->context, val);
client->cache_used = true;
#endif #endif
#ifdef LIBNFS_FEATURE_DEBUG #ifdef LIBNFS_FEATURE_DEBUG
} else if (!strcmp(qp->p[i].name, "debug")) { } else if (!strcmp(qp->p[i].name, "debug")) {
@ -418,7 +425,7 @@ static int nfs_file_open(BlockDriverState *bs, QDict *options, int flags,
} }
ret = nfs_client_open(client, qemu_opt_get(opts, "filename"), ret = nfs_client_open(client, qemu_opt_get(opts, "filename"),
(flags & BDRV_O_RDWR) ? O_RDWR : O_RDONLY, (flags & BDRV_O_RDWR) ? O_RDWR : O_RDONLY,
errp); errp, bs->open_flags);
if (ret < 0) { if (ret < 0) {
goto out; goto out;
} }
@ -454,7 +461,7 @@ static int nfs_file_create(const char *url, QemuOpts *opts, Error **errp)
total_size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0), total_size = ROUND_UP(qemu_opt_get_size_del(opts, BLOCK_OPT_SIZE, 0),
BDRV_SECTOR_SIZE); BDRV_SECTOR_SIZE);
ret = nfs_client_open(client, url, O_CREAT, errp); ret = nfs_client_open(client, url, O_CREAT, errp, 0);
if (ret < 0) { if (ret < 0) {
goto out; goto out;
} }
@ -516,6 +523,11 @@ static int nfs_reopen_prepare(BDRVReopenState *state,
return -EACCES; return -EACCES;
} }
if ((state->flags & BDRV_O_NOCACHE) && client->cache_used) {
error_setg(errp, "Cannot disable cache if libnfs readahead is enabled");
return -EINVAL;
}
/* Update cache for read-only reopens */ /* Update cache for read-only reopens */
if (!(state->flags & BDRV_O_RDWR)) { if (!(state->flags & BDRV_O_RDWR)) {
ret = nfs_fstat(client->context, client->fh, &st); ret = nfs_fstat(client->context, client->fh, &st);