Re: [PATCH U-BOOT v3 25/30] fs: btrfs: Implement btrfs_file_read()

[Tom Rini <trini@konsulko.com>]

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On Wed, Jun 24, 2020 at 06:03:11PM +0200, Marek Behún wrote:

> From: Qu Wenruo <wqu@suse.com>
> 
> This version of btrfs_file_read() has the following new features:
> - Tries all mirrors
> - More handling on unaligned size
> - Better compressed extent handling
>   The old implementation doesn't handle compressed extent with offset
>   properly: we need to read out the whole compressed extent, then
>   decompress the whole extent, and only then copy the requested part.
> 
> Signed-off-by: Qu Wenruo <wqu@suse.com>
> Reviewed-by: Marek Behún <marek.behun@nic.cz>

Note that this introduces a warning with LLVM-10:
fs/btrfs/btrfs.c:246:6: warning: variable 'real_size' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
        if (!len) {
            ^~~~
fs/btrfs/btrfs.c:255:12: note: uninitialized use occurs here
        if (len > real_size - offset)
                  ^~~~~~~~~
fs/btrfs/btrfs.c:246:2: note: remove the 'if' if its condition is always true
        if (!len) {
        ^~~~~~~~~~
fs/btrfs/btrfs.c:228:18: note: initialize the variable 'real_size' to silence this warning
        loff_t real_size;
                        ^
                         = 0
1 warning generated.

and I have silenced as suggested.  I'm not 100% happy with that, but
leave fixing it here and in upstream btrfs-progs to the btrfs-experts.

-- 
Tom

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