Gitweb: https://sourceware.org/git/?p=lvm2.git;a=commitdiff;h=beee9940a503dd6165afd7... Commit: beee9940a503dd6165afd73835d3a6935afcce60 Parent: 145ded10c29a2e76ea12aab98a797e79135d6d44 Author: Alasdair G Kergon agk@redhat.com AuthorDate: Fri Dec 15 21:12:19 2017 +0000 Committer: Alasdair G Kergon agk@redhat.com CommitterDate: Fri Dec 15 21:12:19 2017 +0000

format_text: Separate out code paths for buffer wraparound

The creation of wrapped around metadata - where the start of metadata is written up to the end of the buffer and the remainder follows back at the start of the buffer - is now restricted to cases where writing the metadata in one piece wouldn't fit. This shouldn't happen in 'normal' usage so let's begin treating the code for this as a special case that can be ignored when optimising 'normal' cases. --- lib/config/config.c | 27 +++++++++++++++++++-------- lib/device/dev-io.c | 9 +-------- lib/format_text/format-text.c | 10 ++++++++-- 3 files changed, 28 insertions(+), 18 deletions(-)

diff --git a/lib/config/config.c b/lib/config/config.c index 8fca372..f634e5b 100644 --- a/lib/config/config.c +++ b/lib/config/config.c @@ -504,6 +504,7 @@ int config_file_read_fd(struct dm_config_tree *cft, struct device *dev, dev_io_r int use_mmap = 1; off_t mmap_offset = 0; char *buf = NULL; + unsigned circular = size2 ? 1 : 0; /* Wrapped around end of disk metadata buffer? */ struct config_source *cs = dm_config_get_custom(cft);

if (!_is_file_based_config_source(cs->type)) { @@ -514,7 +515,7 @@ int config_file_read_fd(struct dm_config_tree *cft, struct device *dev, dev_io_r }

/* Only use mmap with regular files */ - if (!(dev->flags & DEV_REGULAR) || size2) + if (!(dev->flags & DEV_REGULAR) || circular) use_mmap = 0;

if (use_mmap) { @@ -528,13 +529,23 @@ int config_file_read_fd(struct dm_config_tree *cft, struct device *dev, dev_io_r } fb = fb + mmap_offset; } else { - if (!(buf = dm_malloc(size + size2))) { - log_error("Failed to allocate circular buffer."); - return 0; - } - if (!dev_read_circular(dev, (uint64_t) offset, size, - (uint64_t) offset2, size2, reason, buf)) { - goto out; + if (circular) { + if (!(buf = dm_malloc(size + size2))) { + log_error("Failed to allocate circular buffer."); + return 0; + } + if (!dev_read_circular(dev, (uint64_t) offset, size, + (uint64_t) offset2, size2, reason, buf)) { + goto out; + } + } else { + if (!(buf = dm_malloc(size))) { + log_error("Failed to allocate buffer for metadata read."); + return 0; + } + if (!dev_read(dev, (uint64_t) offset, size, reason, buf)) { + goto out; + } } fb = buf; } diff --git a/lib/device/dev-io.c b/lib/device/dev-io.c index c321e61..1adf2ad 100644 --- a/lib/device/dev-io.c +++ b/lib/device/dev-io.c @@ -745,7 +745,7 @@ int dev_read(struct device *dev, uint64_t offset, size_t len, dev_io_reason_t re }

/* - * Read from 'dev' into 'buf', possibly in 2 distinct regions, denoted + * Read from 'dev' into 'buf' in 2 distinct regions, denoted * by (offset,len) and (offset2,len2). Thus, the total size of * 'buf' should be len+len2. */ @@ -757,13 +757,6 @@ int dev_read_circular(struct device *dev, uint64_t offset, size_t len, return 0; }

- /* - * The second region is optional, and allows for - * a circular buffer on the device. - */ - if (!len2) - return 1; - if (!dev_read(dev, offset2, len2, reason, buf + len)) { log_error("Circular read from %s failed", dev_name(dev)); diff --git a/lib/format_text/format-text.c b/lib/format_text/format-text.c index ab610ad..ebc2dbb 100644 --- a/lib/format_text/format-text.c +++ b/lib/format_text/format-text.c @@ -185,6 +185,7 @@ static int _pv_analyze_mda_raw (const struct format_type * fmt, char *buf=NULL; struct device_area *area; struct mda_context *mdac; + unsigned circular = 0; int r=0;

mdac = (struct mda_context *) mda->metadata_locn; @@ -236,7 +237,12 @@ static int _pv_analyze_mda_raw (const struct format_type * fmt, if (!(buf = dm_malloc(size + size2))) goto_out;

- if (!dev_read_circular(area->dev, offset, size, offset2, size2, MDA_CONTENT_REASON(mda_is_primary(mda)), buf)) + circular = size2 ? 1 : 0; + + if (circular) { + if (!dev_read_circular(area->dev, offset, size, offset2, size2, MDA_CONTENT_REASON(mda_is_primary(mda)), buf)) + goto_out; + } else if (!dev_read(area->dev, offset, size, MDA_CONTENT_REASON(mda_is_primary(mda)), buf)) goto_out;

/* @@ -708,7 +714,7 @@ static int _vg_write_raw(struct format_instance *fid, struct volume_group *vg, int found = 0; int noprecommit = 0; const char *old_vg_name = NULL; - uint64_t new_size_rounded; + uint64_t new_size_rounded = 0;

/* Ignore any mda on a PV outside the VG. vgsplit relies on this */ dm_list_iterate_items(pvl, &vg->pvs) {