kernel.git/fs/gfs2/bmap.c, branch linux-2.6.28.y

[GFS2] fix gfs2 block allocation (cleaned up)

2008-06-24T18:02:28Z

This patch fixes bz 450641. This patch changes the computation for zero_metapath_length(), which it renames to metapath_branch_start(). When you are extending the metadata tree, The indirect blocks that point to the new data block must either diverge from the existing tree either at the inode, or at the first indirect block. They can diverge at the first indirect block because the inode has room for 483 pointers while the indirect blocks have room for 509 pointers, so when the tree is grown, there is some free space in the first indirect block. What metapath_branch_start() now computes is the height where the first indirect block for the new data block is located. It can either be 1 (if the indirect block diverges from the inode) or 2 (if it diverges from the first indirect block). Signed-off-by: Benjamin Marzinski Signed-off-by: Steven Whitehouse

[GFS2] Streamline quota lock/check for no-quota case

2008-03-31T09:41:36Z

This patch streamlines the quota checking in the "no quota" case by making the check inline in the calling function, thus reducing the number of function calls. Eventually we might be able to remove the checks from the gfs2_quota_lock() and gfs2_quota_check() functions, but currently we can't as there are a very few places in the code which need to call these functions directly still. Signed-off-by: Steven Whitehouse Cc: Abhijith Das

[GFS2] possible null pointer dereference fixup

2008-03-31T09:41:28Z

gfs2_alloc_get may fail so we have to check it to prevent NULL pointer dereference. Signed-off-by: Cyrill Gorcunov Signed-off-by: Steven Whitehouse

[GFS2] Allow bmap to allocate extents

2008-03-31T09:41:14Z

We've supported mapping of extents when no block allocation is required for some time. This patch extends that to mapping of extents when an allocation has been requested. In that case we try to allocate as many blocks as are requested, but we might return fewer in case there is something preventing us from returning the complete amount (e.g. an already allocated block is in the way). Currently the only code path which can actually request multiple data blocks in a single bmap call is the page_mkwrite path and even then it only happens if there are multiple blocks per page. What this patch does do however, is merge the allocation requests for metadata (growing the metadata tree in either height or depth) with the allocation of the data blocks in the case that both are needed. This results in lower overheads even in the single block allocation case. The one thing which we can't handle here at the moment is unstuffing. I would like to be able to do that, but the problem which arises is that in order to unstuff one has to get a locked page from the page cache which results in locking problems in the (usual) case that the caller is holding the page lock on the page it wishes to map. So that case will have to be addressed in future patches. Signed-off-by: Steven Whitehouse

[GFS2] Get inode buffer only once per block map call

2008-03-31T09:40:58Z

In the case that we needed to grow the height of the metadata tree we were looking up the inode buffer and then brelse()ing it despite the fact that it is needed later in the block map process. This patch ensures that we look up the inode's buffer once and only once during the block map process. Signed-off-by: Steven Whitehouse

[GFS2] Eliminate (almost) duplicate field from gfs2_inode

2008-03-31T09:40:55Z

The blocks counter is almost a duplicate of the i_blocks field in the VFS inode. The only difference is that i_blocks can be only 32bits long for 32bit arch without large single file support. Since GFS2 doesn't handle the non-large single file case (for 32 bit anyway) this adds a new config dependency on 64BIT || LSF. This has always been the case, however we've never explicitly said so before. Even if we do add support for the non-LSF case, we will still not require this field to be duplicated since we will not be able to access oversized files anyway. So the net result of all this is that we shave 8 bytes from a gfs2_inode and get our config deps correct. Signed-off-by: Steven Whitehouse

[GFS2] Add a function to interate over an extent

2008-03-31T09:40:53Z

This adds a function (currently the only use is during mapping of already allocated blocks, but watch this space) which iterates over a number of pointers in a block and returns the extent length. If the initial pointer is 0 (i.e. unallocated) it will return the number of unallocated blocks in the extent. If the initial pointer is allocated, then it returns the number of contiguously allocated blocks in the extent. Signed-off-by: Steven Whitehouse

[GFS2] The case of the missing asterisk

2008-03-31T09:40:50Z

A dereference was forgotten. This adds it back correctly. Signed-off-by: Steven Whitehouse

[GFS2] Add extent allocation to block allocator

2008-03-31T09:40:47Z

Rather than having to allocate a single block at a time, this patch allows the block allocator to allocate an extent. Since there is no difference (so far as the block allocator is concerned) between data blocks and indirect blocks, it is posible to allocate a single extent and for the caller to unrevoke just the blocks required for indirect blocks. Currently the only bit of GFS2 to make use of this feature is the build height function. The intention is that gfs2_block_map will be changed to make use of this feature in future patches. Signed-off-by: Steven Whitehouse

[GFS2] Merge gfs2_alloc_meta and gfs2_alloc_data

2008-03-31T09:40:45Z

Thanks to the preceeding patches, the only difference between these two functions is their name. We can thus merge them and call the new function gfs2_alloc_block to reflect the fact that it can allocate either kind of block. Signed-off-by: Steven Whitehouse