From 18a8056e0bc744e5dd2bb5cb998423b607d99f19 Mon Sep 17 00:00:00 2001 From: Peter Lieven Date: Thu, 27 Aug 2015 12:30:41 +0200 Subject: [PATCH] block/nfs: cache allocated filesize for read-only files If the file is readonly its not expected to grow so save the blocking call to nfs_fstat_async and use the value saved at connection time. Also important the monitor (and thus the main loop) will not hang if block device info is queried and the NFS share is unresponsive. Signed-off-by: Peter Lieven Reviewed-by: Jeff Cody Reviewed-by: Max Reitz Message-id: 1440671441-7978-1-git-send-email-pl@kamp.de Signed-off-by: Jeff Cody --- block/nfs.c | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) diff --git a/block/nfs.c b/block/nfs.c index 02eb4e4643..887a98e3fc 100644 --- a/block/nfs.c +++ b/block/nfs.c @@ -43,6 +43,7 @@ typedef struct NFSClient { int events; bool has_zero_init; AioContext *aio_context; + blkcnt_t st_blocks; } NFSClient; typedef struct NFSRPC { @@ -374,6 +375,7 @@ static int64_t nfs_client_open(NFSClient *client, const char *filename, } ret = DIV_ROUND_UP(st.st_size, BDRV_SECTOR_SIZE); + client->st_blocks = st.st_blocks; client->has_zero_init = S_ISREG(st.st_mode); goto out; fail: @@ -464,6 +466,11 @@ static int64_t nfs_get_allocated_file_size(BlockDriverState *bs) NFSRPC task = {0}; struct stat st; + if (bdrv_is_read_only(bs) && + !(bs->open_flags & BDRV_O_NOCACHE)) { + return client->st_blocks * 512; + } + task.st = &st; if (nfs_fstat_async(client->context, client->fh, nfs_co_generic_cb, &task) != 0) { @@ -484,6 +491,34 @@ static int nfs_file_truncate(BlockDriverState *bs, int64_t offset) return nfs_ftruncate(client->context, client->fh, offset); } +/* Note that this will not re-establish a connection with the NFS server + * - it is effectively a NOP. */ +static int nfs_reopen_prepare(BDRVReopenState *state, + BlockReopenQueue *queue, Error **errp) +{ + NFSClient *client = state->bs->opaque; + struct stat st; + int ret = 0; + + if (state->flags & BDRV_O_RDWR && bdrv_is_read_only(state->bs)) { + error_setg(errp, "Cannot open a read-only mount as read-write"); + return -EACCES; + } + + /* Update cache for read-only reopens */ + if (!(state->flags & BDRV_O_RDWR)) { + ret = nfs_fstat(client->context, client->fh, &st); + if (ret < 0) { + error_setg(errp, "Failed to fstat file: %s", + nfs_get_error(client->context)); + return ret; + } + client->st_blocks = st.st_blocks; + } + + return 0; +} + static BlockDriver bdrv_nfs = { .format_name = "nfs", .protocol_name = "nfs", @@ -499,6 +534,7 @@ static BlockDriver bdrv_nfs = { .bdrv_file_open = nfs_file_open, .bdrv_close = nfs_file_close, .bdrv_create = nfs_file_create, + .bdrv_reopen_prepare = nfs_reopen_prepare, .bdrv_co_readv = nfs_co_readv, .bdrv_co_writev = nfs_co_writev,