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Filipe Manana a79c3a99ac btrfs: fix failure of RWF_NOWAIT write into prealloc extent beyond eof 
commit 4b1946284d upstream.

If we attempt to write to prealloc extent located after eof using a
RWF_NOWAIT write, we always fail with -EAGAIN.

We do actually check if we have an allocated extent for the write at
the start of btrfs_file_write_iter() through a call to check_can_nocow(),
but later when we go into the actual direct IO write path we simply
return -EAGAIN if the write starts at or beyond EOF.

Trivial to reproduce:

  $ mkfs.btrfs -f /dev/sdb
  $ mount /dev/sdb /mnt

  $ touch /mnt/foo
  $ chattr +C /mnt/foo

  $ xfs_io -d -c "pwrite -S 0xab 0 64K" /mnt/foo
  wrote 65536/65536 bytes at offset 0
  64 KiB, 16 ops; 0.0004 sec (135.575 MiB/sec and 34707.1584 ops/sec)

  $ xfs_io -c "falloc -k 64K 1M" /mnt/foo

  $ xfs_io -d -c "pwrite -N -V 1 -S 0xfe -b 64K 64K 64K" /mnt/foo
  pwrite: Resource temporarily unavailable

On xfs and ext4 the write succeeds, as expected.

Fix this by removing the wrong check at btrfs_direct_IO().

Fixes: edf064e7c6 ("btrfs: nowait aio support")
CC: stable@vger.kernel.org # 4.14+
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 		2020-06-30 15:37:08 -04:00
Documentation dt-bindings: display: mediatek: control dpi pins mode to avoid leakage 2020-06-22 09:30:58 +02:00
LICENSES
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arch x86/asm/64: Align start of __clear_user() loop to 16-bytes 2020-06-30 15:37:08 -04:00
block block: update hctx map when use multiple maps 2020-06-30 15:37:06 -04:00
certs
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crypto crypto: algboss - don't wait during notifier callback 2020-06-24 17:50:51 +02:00
drivers ACPI: configfs: Disallow loading ACPI tables when locked down 2020-06-30 15:37:07 -04:00
fs btrfs: fix failure of RWF_NOWAIT write into prealloc extent beyond eof 2020-06-30 15:37:08 -04:00
include net: qed: fix left elements count calculation 2020-06-30 15:36:58 -04:00
init x86: Fix early boot crash on gcc-10, third try 2020-05-20 08:20:34 +02:00
ipc ipc/util.c: sysvipc_find_ipc() incorrectly updates position index 2020-05-20 08:20:16 +02:00
kernel blktrace: break out of blktrace setup on concurrent calls 2020-06-30 15:37:05 -04:00
lib test_objagg: Fix potential memory leak in error handling 2020-06-30 15:37:04 -04:00
mm mm: call cond_resched() from deferred_init_memmap() 2020-06-22 09:31:14 +02:00
net netfilter: ipset: fix unaligned atomic access 2020-06-30 15:37:01 -04:00
samples bpf, xdp, samples: Fix null pointer dereference in *_user code 2020-06-30 15:36:55 -04:00
scripts recordmcount: support >64k sections 2020-06-30 15:37:05 -04:00
security selinux: fix double free 2020-06-24 17:50:48 +02:00
sound ALSA: hda/realtek: Add mute LED and micmute LED support for HP systems 2020-06-30 15:37:06 -04:00
tools selftests/net: report etf errors correctly 2020-06-30 15:36:58 -04:00
usr initramfs: restore default compression behavior 2020-04-08 09:08:38 +02:00
virt KVM: arm64: Save the host's PtrAuth keys in non-preemptible context 2020-06-17 16:40:38 +02:00
.clang-format
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.cocciconfig
…
.get_maintainer.ignore
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.gitattributes
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.gitignore Modules updates for v5.4 2019-09-22 10:34:46 -07:00
.mailmap ARM: SoC fixes 2019-11-10 13:41:59 -08:00
COPYING
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CREDITS MAINTAINERS: Remove Simon as Renesas SoC Co-Maintainer 2019-10-10 08:12:51 -07:00
Kbuild
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Kconfig
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MAINTAINERS MAINTAINERS: Update drm/i915 bug filing URL 2020-02-28 17:22:19 +01:00
Makefile Linux 5.4.49 2020-06-24 17:50:53 +02:00
README
…

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.