From ab2add35decbf3f5f0373f785a799ed879646c7c Mon Sep 17 00:00:00 2001 From: Naphtali Sprei Date: Wed, 7 Apr 2010 16:44:24 -0300 Subject: [PATCH 13/21] block: more read-only changes, related to backing files RH-Author: Naphtali Sprei Message-id: <1270658667-14294-14-git-send-email-nsprei@redhat.com> Patchwork-id: 8446 O-Subject: [RHEL6 kvm PATCH v3 rebase 13/16] block: more read-only changes, related to backing files Bugzilla: 537164 RH-Acked-by: Daniel P. Berrange RH-Acked-by: Christoph Hellwig RH-Acked-by: Juan Quintela RH-Acked-by: Kevin Wolf Open backing file read-only where possible Upgrade backing file to read-write during commit, back to read-only after commit If upgrade fail, back to read-only. If also fail, "disconnect" the drive. BZ: https://bugzilla.redhat.com/show_bug.cgi?id=537164 upstream commit: 4dca4b639cb20fee38f6eec0a391aecc0ad8848d Signed-off-by: Naphtali Sprei Signed-off-by: Anthony Liguori --- block.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++-------- block_int.h | 2 + 2 files changed, 72 insertions(+), 11 deletions(-) Signed-off-by: Eduardo Habkost --- block.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++-------- block_int.h | 2 + 2 files changed, 72 insertions(+), 11 deletions(-) diff --git a/block.c b/block.c index 9252184..9e76024 100644 --- a/block.c +++ b/block.c @@ -363,6 +363,7 @@ int bdrv_open2(BlockDriverState *bs, const char *filename, int flags, bs->is_temporary = 0; bs->encrypted = 0; bs->valid_key = 0; + bs->open_flags = flags; /* buffer_alignment defaulted to 512, drivers can change this value */ bs->buffer_alignment = 512; @@ -450,8 +451,6 @@ int bdrv_open2(BlockDriverState *bs, const char *filename, int flags, if (flags & (BDRV_O_CACHE_WB|BDRV_O_NOCACHE)) bs->enable_write_cache = 1; - bs->read_only = (flags & BDRV_O_RDWR) == 0; - /* * Clear flags that are internal to the block layer before opening the * image. @@ -472,6 +471,7 @@ int bdrv_open2(BlockDriverState *bs, const char *filename, int flags, goto free_and_fail; } + bs->keep_read_only = bs->read_only = !(open_flags & BDRV_O_RDWR); if (drv->bdrv_getlength) { bs->total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS; } @@ -488,13 +488,22 @@ int bdrv_open2(BlockDriverState *bs, const char *filename, int flags, filename, bs->backing_file); if (bs->backing_format[0] != '\0') back_drv = bdrv_find_format(bs->backing_format); + + /* backing files always opened read-only */ + open_flags &= ~BDRV_O_RDWR; + ret = bdrv_open2(bs->backing_hd, backing_filename, open_flags, back_drv); - bs->backing_hd->read_only = (open_flags & BDRV_O_RDWR) == 0; if (ret < 0) { bdrv_close(bs); return ret; } + if (bs->is_temporary) { + bs->backing_hd->keep_read_only = !(flags & BDRV_O_RDWR); + } else { + /* base image inherits from "parent" */ + bs->backing_hd->keep_read_only = bs->keep_read_only; + } } if (!bdrv_key_required(bs)) { @@ -570,19 +579,48 @@ int bdrv_commit(BlockDriverState *bs) { BlockDriver *drv = bs->drv; int64_t i, total_sectors; - int n, j; - int ret = 0; + int n, j, ro, open_flags; + int ret = 0, rw_ret = 0; unsigned char sector[512]; + char filename[1024]; + BlockDriverState *bs_rw, *bs_ro; if (!drv) return -ENOMEDIUM; - if (bs->read_only) { - return -EACCES; + if (!bs->backing_hd) { + return -ENOTSUP; } - if (!bs->backing_hd) { - return -ENOTSUP; + if (bs->backing_hd->keep_read_only) { + return -EACCES; + } + + ro = bs->backing_hd->read_only; + strncpy(filename, bs->backing_hd->filename, sizeof(filename)); + open_flags = bs->backing_hd->open_flags; + + if (ro) { + /* re-open as RW */ + bdrv_delete(bs->backing_hd); + bs->backing_hd = NULL; + bs_rw = bdrv_new(""); + rw_ret = bdrv_open2(bs_rw, filename, open_flags | BDRV_O_RDWR, NULL); + if (rw_ret < 0) { + bdrv_delete(bs_rw); + /* try to re-open read-only */ + bs_ro = bdrv_new(""); + ret = bdrv_open2(bs_ro, filename, open_flags & ~BDRV_O_RDWR, NULL); + if (ret < 0) { + bdrv_delete(bs_ro); + /* drive not functional anymore */ + bs->drv = NULL; + return ret; + } + bs->backing_hd = bs_ro; + return rw_ret; + } + bs->backing_hd = bs_rw; } total_sectors = bdrv_getlength(bs) >> BDRV_SECTOR_BITS; @@ -590,11 +628,13 @@ int bdrv_commit(BlockDriverState *bs) if (drv->bdrv_is_allocated(bs, i, 65536, &n)) { for(j = 0; j < n; j++) { if (bdrv_read(bs, i, sector, 1) != 0) { - return -EIO; + ret = -EIO; + goto ro_cleanup; } if (bdrv_write(bs->backing_hd, i, sector, 1) != 0) { - return -EIO; + ret = -EIO; + goto ro_cleanup; } i++; } @@ -614,6 +654,25 @@ int bdrv_commit(BlockDriverState *bs) */ if (bs->backing_hd) bdrv_flush(bs->backing_hd); + +ro_cleanup: + + if (ro) { + /* re-open as RO */ + bdrv_delete(bs->backing_hd); + bs->backing_hd = NULL; + bs_ro = bdrv_new(""); + ret = bdrv_open2(bs_ro, filename, open_flags & ~BDRV_O_RDWR, NULL); + if (ret < 0) { + bdrv_delete(bs_ro); + /* drive not functional anymore */ + bs->drv = NULL; + return ret; + } + bs->backing_hd = bs_ro; + bs->backing_hd->keep_read_only = 0; + } + return ret; } diff --git a/block_int.h b/block_int.h index a0ebd90..93669da 100644 --- a/block_int.h +++ b/block_int.h @@ -130,6 +130,8 @@ struct BlockDriverState { int64_t total_sectors; /* if we are reading a disk image, give its size in sectors */ int read_only; /* if true, the media is read only */ + int keep_read_only; /* if true, the media was requested to stay read only */ + int open_flags; /* flags used to open the file, re-used for re-open */ int removable; /* if true, the media can be removed */ int locked; /* if true, the media cannot temporarily be ejected */ int encrypted; /* if true, the media is encrypted */ -- 1.7.0.3