1. 15 Mar, 2010 1 commit
  2. 11 Sep, 2009 1 commit
    • Chris Mason's avatar
      Btrfs: switch extent_map to a rw lock · 890871be
      Chris Mason authored
      
      
      There are two main users of the extent_map tree.  The
      first is regular file inodes, where it is evenly spread
      between readers and writers.
      
      The second is the chunk allocation tree, which maps blocks from
      logical addresses to phyiscal ones, and it is 99.99% reads.
      
      The mapping tree is a point of lock contention during heavy IO
      workloads, so this commit switches things to a rw lock.
      Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
      890871be
  3. 12 Jul, 2009 1 commit
  4. 10 Jun, 2009 1 commit
    • Christoph Hellwig's avatar
      Btrfs: implement FS_IOC_GETFLAGS/SETFLAGS/GETVERSION · 6cbff00f
      Christoph Hellwig authored
      
      
      Add support for the standard attributes set via chattr and read via
      lsattr.  Currently we store the attributes in the flags value in
      the btrfs inode, but I wonder whether we should split it into two so
      that we don't have to keep converting between the two formats.
      
      Remove the btrfs_clear_flag/btrfs_set_flag/btrfs_test_flag macros
      as they were confusing the existing code and got in the way of the
      new additions.
      
      Also add the FS_IOC_GETVERSION ioctl for getting i_generation as it's
      trivial.
      Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
      Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
      6cbff00f
  5. 21 Jan, 2009 1 commit
  6. 05 Jan, 2009 1 commit
  7. 12 Dec, 2008 1 commit
    • Yan Zheng's avatar
      Btrfs: fix nodatasum handling in balancing code · 17d217fe
      Yan Zheng authored
      
      
      Checksums on data can be disabled by mount option, so it's
      possible some data extents don't have checksums or have
      invalid checksums. This causes trouble for data relocation.
      This patch contains following things to make data relocation
      work.
      
      1) make nodatasum/nodatacow mount option only affects new
      files. Checksums and COW on data are only controlled by the
      inode flags.
      
      2) check the existence of checksum in the nodatacow checker.
      If checksums exist, force COW the data extent. This ensure that
      checksum for a given block is either valid or does not exist.
      
      3) update data relocation code to properly handle the case
      of checksum missing.
      Signed-off-by: default avatarYan Zheng <zheng.yan@oracle.com>
      17d217fe
  8. 08 Dec, 2008 1 commit
    • Chris Mason's avatar
      Btrfs: move data checksumming into a dedicated tree · d20f7043
      Chris Mason authored
      
      
      Btrfs stores checksums for each data block.  Until now, they have
      been stored in the subvolume trees, indexed by the inode that is
      referencing the data block.  This means that when we read the inode,
      we've probably read in at least some checksums as well.
      
      But, this has a few problems:
      
      * The checksums are indexed by logical offset in the file.  When
      compression is on, this means we have to do the expensive checksumming
      on the uncompressed data.  It would be faster if we could checksum
      the compressed data instead.
      
      * If we implement encryption, we'll be checksumming the plain text and
      storing that on disk.  This is significantly less secure.
      
      * For either compression or encryption, we have to get the plain text
      back before we can verify the checksum as correct.  This makes the raid
      layer balancing and extent moving much more expensive.
      
      * It makes the front end caching code more complex, as we have touch
      the subvolume and inodes as we cache extents.
      
      * There is potentitally one copy of the checksum in each subvolume
      referencing an extent.
      
      The solution used here is to store the extent checksums in a dedicated
      tree.  This allows us to index the checksums by phyiscal extent
      start and length.  It means:
      
      * The checksum is against the data stored on disk, after any compression
      or encryption is done.
      
      * The checksum is stored in a central location, and can be verified without
      following back references, or reading inodes.
      
      This makes compression significantly faster by reducing the amount of
      data that needs to be checksummed.  It will also allow much faster
      raid management code in general.
      
      The checksums are indexed by a key with a fixed objectid (a magic value
      in ctree.h) and offset set to the starting byte of the extent.  This
      allows us to copy the checksum items into the fsync log tree directly (or
      any other tree), without having to invent a second format for them.
      Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
      d20f7043
  9. 20 Nov, 2008 1 commit
  10. 19 Nov, 2008 1 commit
  11. 11 Nov, 2008 1 commit
  12. 10 Nov, 2008 2 commits
  13. 07 Nov, 2008 1 commit
    • Chris Mason's avatar
      Btrfs: make sure compressed bios don't complete too soon · af09abfe
      Chris Mason authored
      
      
      When writing a compressed extent, a number of bios are created that
      point to a single struct compressed_bio.  At end_io time an atomic counter in
      the compressed_bio struct makes sure that all of the bios have finished
      before final end_io processing is done.
      
      But when multiple bios are needed to write a compressed extent, the
      counter was being incremented after the first bio was sent to submit_bio.
      It is possible the bio will complete before the counter is incremented,
      making the end_io handler free the compressed_bio struct before
      processing is finished.
      
      The fix is to increment the atomic counter before bio submission,
      both for compressed reads and writes.
      Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
      af09abfe
  14. 06 Nov, 2008 1 commit
    • Chris Mason's avatar
      Btrfs: Optimize compressed writeback and reads · 771ed689
      Chris Mason authored
      
      
      When reading compressed extents, try to put pages into the page cache
      for any pages covered by the compressed extent that readpages didn't already
      preload.
      
      Add an async work queue to handle transformations at delayed allocation processing
      time.  Right now this is just compression.  The workflow is:
      
      1) Find offsets in the file marked for delayed allocation
      2) Lock the pages
      3) Lock the state bits
      4) Call the async delalloc code
      
      The async delalloc code clears the state lock bits and delalloc bits.  It is
      important this happens before the range goes into the work queue because
      otherwise it might deadlock with other work queue items that try to lock
      those extent bits.
      
      The file pages are compressed, and if the compression doesn't work the
      pages are written back directly.
      
      An ordered work queue is used to make sure the inodes are written in the same
      order that pdflush or writepages sent them down.
      
      This changes extent_write_cache_pages to let the writepage function
      update the wbc nr_written count.
      Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
      771ed689
  15. 31 Oct, 2008 1 commit
    • Chris Mason's avatar
      Btrfs: Compression corner fixes · 70b99e69
      Chris Mason authored
      
      
      Make sure we keep page->mapping NULL on the pages we're getting
      via alloc_page.  It gets set so a few of the callbacks can do the right
      thing, but in general these pages don't have a mapping.
      
      Don't try to truncate compressed inline items in btrfs_drop_extents.
      The whole compressed item must be preserved.
      
      Don't try to create multipage inline compressed items.  When we try to
      overwrite just the first page of the file, we would have to read in and recow
      all the pages after it in the same compressed inline items.  For now, only
      create single page inline items.
      
      Make sure we lock pages in the correct order during delalloc.  The
      search into the state tree for delalloc bytes can return bytes before
      the page we already have locked.
      Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
      70b99e69
  16. 30 Oct, 2008 1 commit
  17. 29 Oct, 2008 1 commit
    • Chris Mason's avatar
      Btrfs: Add zlib compression support · c8b97818
      Chris Mason authored
      
      
      This is a large change for adding compression on reading and writing,
      both for inline and regular extents.  It does some fairly large
      surgery to the writeback paths.
      
      Compression is off by default and enabled by mount -o compress.  Even
      when the -o compress mount option is not used, it is possible to read
      compressed extents off the disk.
      
      If compression for a given set of pages fails to make them smaller, the
      file is flagged to avoid future compression attempts later.
      
      * While finding delalloc extents, the pages are locked before being sent down
      to the delalloc handler.  This allows the delalloc handler to do complex things
      such as cleaning the pages, marking them writeback and starting IO on their
      behalf.
      
      * Inline extents are inserted at delalloc time now.  This allows us to compress
      the data before inserting the inline extent, and it allows us to insert
      an inline extent that spans multiple pages.
      
      * All of the in-memory extent representations (extent_map.c, ordered-data.c etc)
      are changed to record both an in-memory size and an on disk size, as well
      as a flag for compression.
      
      From a disk format point of view, the extent pointers in the file are changed
      to record the on disk size of a given extent and some encoding flags.
      Space in the disk format is allocated for compression encoding, as well
      as encryption and a generic 'other' field.  Neither the encryption or the
      'other' field are currently used.
      
      In order to limit the amount of data read for a single random read in the
      file, the size of a compressed extent is limited to 128k.  This is a
      software only limit, the disk format supports u64 sized compressed extents.
      
      In order to limit the ram consumed while processing extents, the uncompressed
      size of a compressed extent is limited to 256k.  This is a software only limit
      and will be subject to tuning later.
      
      Checksumming is still done on compressed extents, and it is done on the
      uncompressed version of the data.  This way additional encodings can be
      layered on without having to figure out which encoding to checksum.
      
      Compression happens at delalloc time, which is basically singled threaded because
      it is usually done by a single pdflush thread.  This makes it tricky to
      spread the compression load across all the cpus on the box.  We'll have to
      look at parallel pdflush walks of dirty inodes at a later time.
      
      Decompression is hooked into readpages and it does spread across CPUs nicely.
      Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
      c8b97818