[pbs-devel] [RFC proxmox-backup] tape: lock media_catalog file to to get a consistent view with load_catalog
Dietmar Maurer
dietmar at proxmox.com
Wed Jul 28 10:28:29 CEST 2021
---
src/tape/media_catalog.rs | 22 ++++++++++++++++++----
1 file changed, 18 insertions(+), 4 deletions(-)
diff --git a/src/tape/media_catalog.rs b/src/tape/media_catalog.rs
index 62c6acb3..1bd136f9 100644
--- a/src/tape/media_catalog.rs
+++ b/src/tape/media_catalog.rs
@@ -231,7 +231,12 @@ impl MediaCatalog {
pending: Vec::new(),
};
- let (found_magic_number, _) = me.load_catalog(&mut file, media_id.media_set_label.as_ref())?;
+ // Note: lock file, to get a consistent view with load_catalog
+ nix::fcntl::flock(file.as_raw_fd(), nix::fcntl::FlockArg::LockExclusive)?;
+ let result = me.load_catalog(&mut file, media_id.media_set_label.as_ref());
+ nix::fcntl::flock(file.as_raw_fd(), nix::fcntl::FlockArg::Unlock)?;
+
+ let (found_magic_number, _) = result?;
if !found_magic_number {
me.pending.extend(&Self::PROXMOX_BACKUP_MEDIA_CATALOG_MAGIC_1_1);
@@ -372,9 +377,18 @@ impl MediaCatalog {
match self.file {
Some(ref mut file) => {
- file.write_all(&self.pending)?;
- file.flush()?;
- file.sync_data()?;
+ let pending = &self.pending;
+ // Note: lock file, to get a consistent view with load_catalog
+ nix::fcntl::flock(file.as_raw_fd(), nix::fcntl::FlockArg::LockExclusive)?;
+ let result: Result<(), Error> = proxmox::try_block!({
+ file.write_all(pending)?;
+ file.flush()?;
+ file.sync_data()?;
+ Ok(())
+ });
+ nix::fcntl::flock(file.as_raw_fd(), nix::fcntl::FlockArg::Unlock)?;
+
+ result?;
}
None => bail!("media catalog not writable (opened read only)"),
}
--
2.30.2
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