Summary of what I've managed to rule out so far: 1. this problem does not occur without dm-crypt 2. this problem does not occur when the file system hasn't been moved from the SATA disk to USB 3. Both reiserfs and ext3 are affected by this problem, but ext3 merely slows down. 4. Unmounting and re-mounting has no effect. My initial report contains more details. On 3/22/07, Alasdair G Kergon <agk@xxxxxxxxxx> wrote:
A couple of patches to try: dm-io-fix-bi_max_vecs.patch dm-merge-max_hw_sector.patch and perhaps these three: dm-crypt-fix-call-to-clone_init.patch dm-crypt-fix-avoid-cloned-bio-ref-after-free.patch dm-crypt-fix-remove-first_clone.patch
No luck. :( And thanks for reminding me how annoying reboots are... On 3/21/07, Lennart Sorensen <lsorense@xxxxxxxxxxxxxxxxxxx> wrote:
Does this happen only with this combination, or can you elliminate something as the cause?
Doesn't occur if dm-crypt is not involved (e.g., when placing reiserfs or ext3 straight on top of /dev/primary/punchbag). I don't know if LVM is necessary, as I don't have any unallocated space for "oldschool" partitions left. Nor do these problems occur when creating either file system directly on the USB disk -- so, only when they have been lvmoved from the SATA disk, or when the volume is physically dd'ed to the USB disk. On 3/21/07, Lennart Sorensen <lsorense@xxxxxxxxxxxxxxxxxxx> wrote:
Does it happen with ext3 or only reiserfs?
Tried with ext3 (LVM+dm-crypt+ext3), and the files didn't appear corrupt, however, I could still see those messages in my dmesg, and disk access was *extremely* slow, causing around 10k context switches per second (!?) reading below 5 MB/s. Normally, I can get read speeds around 12-22 MB/s with this particular USB disk. However, it's not CPU-bound, as over >80% of CPU is still spent in iowait. When the ext3 file system is created directly on a volume that is located on the USB disk, however, these problems do not occur, just like with reiserfs. However, when I copied the same files to a reiserfs volume when the LV had already been pvmoved to /dev/sdb, the files were readable (as pointed out in my initial post). Interestingly, it did not introduce the same slowdown as with ext3, reading around 13-14 MB/s with ~3k context switches per second. To clarify (I double-checked all these scenarios): (1) files written *before* pvmove are corrupt with reiserfs (2) files written *after* pvmove read fast with reiserfs (3) files written *before* pvmove read slowly with ext3 (4) files written *after* pvmove read slowly with ext3 (5) files written to an ext3 volume that was formatted on the USB disk and not pvmoved are fast and don't report these dmesg warnings. This is purely my speculation, and I can't pretend to know much about the inner workings of device-mapper/file systems, but it appears that ext3 statically derives some attributes during the creation of a file system, while reiserfs gets them runtime. ext3 contains a slow workaround if these attributes don't match (and still posts a warning), but reiserfs returns outright I/O errors. (P.S. does the LKML archive randomly omit some double-newlines in posts, or is this a problem on my end?) Marti Raudsepp -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
