On 8/21/20 3:38 AM, Omar Sandoval wrote:
From: Omar Sandoval <osandov@xxxxxx>
There are 4 main cases:
1. Inline extents: we copy the data straight out of the extent buffer.
2. Hole/preallocated extents: we fill in zeroes.
3. Regular, uncompressed extents: we read the sectors we need directly
from disk.
4. Regular, compressed extents: we read the entire compressed extent
from disk and indicate what subset of the decompressed extent is in
the file.
This initial implementation simplifies a few things that can be improved
in the future:
- We hold the inode lock during the operation.
- Cases 1, 3, and 4 allocate temporary memory to read into before
copying out to userspace.
Signed-off-by: Omar Sandoval <osandov@xxxxxx>
<snip>
+ tmp = kmalloc(count, GFP_NOFS);
+ if (!tmp) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ read_extent_buffer(leaf, tmp, ptr, count);
+ btrfs_free_path(path);
Why not just btrfs_release_path(), you're freeing below anyway.
Also a mention that we're explicitly not handling read repairs and backup copies
would be good in the changelog as well. Thanks,
Josef
