Chris Mason <chris.mason@xxxxxxxxxx> wrote: > On Sun, 2009-03-29 at 12:22 +0100, Måns Rullgård wrote: >> Consider this scenario: >> >> 1. Create/write/close newfile >> 2. Rename newfile to oldfile > > 2a. create oldfile again > 2b. fsync oldfile > >> 3. Open/read oldfile. This must return the new contents. >> 4. System crash and reboot before delayed allocation/flush complete >> 5. Open/read oldfile. Old contents now returned. >> > > What happens to the new generation of oldfile? We could insert > dependency tracking so that we know the fsync of oldfile is supposed to > also fsync the rename'd new file. If rename() is BEFORE create(oldfile) and if create(oldfile) is committed, oldfile will be the newly created file. If the sync() is interrupted by the crash, any intermediate state may appear. If the system crashes before create(), either the old oldfile or newfile should be visible. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
