linux.git/fs/ext4/inode.c, branch v5.3

Revert "ext4: make __ext4_get_inode_loc plug"

2019-09-15T19:32:03+00:00

This reverts commit b03755ad6f33b7b8cd7312a3596a2dbf496de6e7.

This is sad, and done for all the wrong reasons.  Because that commit is
good, and does exactly what it says: avoids a lot of small disk requests
for the inode table read-ahead.

However, it turns out that it causes an entirely unrelated problem: the
getrandom() system call was introduced back in 2014 by commit
c6e9d6f38894 ("random: introduce getrandom(2) system call"), and people
use it as a convenient source of good random numbers.

But part of the current semantics for getrandom() is that it waits for
the entropy pool to fill at least partially (unlike /dev/urandom).  And
at least ArchLinux apparently has a systemd that uses getrandom() at
boot time, and the improvements in IO patterns means that existing
installations suddenly start hanging, waiting for entropy that will
never happen.

It seems to be an unlucky combination of not _quite_ enough entropy,
together with a particular systemd version and configuration.  Lennart
says that the systemd-random-seed process (which is what does this early
access) is supposed to not block any other boot activity, but sadly that
doesn't actually seem to be the case (possibly due bogus dependencies on
cryptsetup for encrypted swapspace).

The correct fix is to fix getrandom() to not block when it's not
appropriate, but that fix is going to take a lot more discussion.  Do we
just make it act like /dev/urandom by default, and add a new flag for
"wait for entropy"? Do we add a boot-time option? Or do we just limit
the amount of time it will wait for entropy?

So in the meantime, we do the revert to give us time to discuss the
eventual fix for the fundamental problem, at which point we can re-apply
the ext4 inode table access optimization.

Reported-by: Ahmed S. Darwish 
Cc: Ted Ts'o 
Cc: Willy Tarreau 
Cc: Alexander E. Patrakov 
Cc: Lennart Poettering 
Signed-off-by: Linus Torvalds

Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

2019-07-11T04:06:01+00:00

Pull ext4 updates from Ted Ts'o:
 "Many bug fixes and cleanups, and an optimization for case-insensitive
  lookups"

* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
  ext4: fix coverity warning on error path of filename setup
  ext4: replace ktype default_attrs with default_groups
  ext4: rename htree_inline_dir_to_tree() to ext4_inlinedir_to_tree()
  ext4: refactor initialize_dirent_tail()
  ext4: rename "dirent_csum" functions to use "dirblock"
  ext4: allow directory holes
  jbd2: drop declaration of journal_sync_buffer()
  ext4: use jbd2_inode dirty range scoping
  jbd2: introduce jbd2_inode dirty range scoping
  mm: add filemap_fdatawait_range_keep_errors()
  ext4: remove redundant assignment to node
  ext4: optimize case-insensitive lookups
  ext4: make __ext4_get_inode_loc plug
  ext4: clean up kerneldoc warnigns when building with W=1
  ext4: only set project inherit bit for directory
  ext4: enforce the immutable flag on open files
  ext4: don't allow any modifications to an immutable file
  jbd2: fix typo in comment of journal_submit_inode_data_buffers
  jbd2: fix some print format mistakes
  ext4: gracefully handle ext4_break_layouts() failure during truncate

ext4: use jbd2_inode dirty range scoping

2019-06-20T21:26:26+00:00

Use the newly introduced jbd2_inode dirty range scoping to prevent us
from waiting forever when trying to complete a journal transaction.

Signed-off-by: Ross Zwisler 
Signed-off-by: Theodore Ts'o 
Reviewed-by: Jan Kara 
Cc: stable@vger.kernel.org

ext4: make __ext4_get_inode_loc plug

2019-06-20T03:41:29+00:00

Add a blk_plug to prevent the inode table readahead from being
submitted as small I/O requests.

Signed-off-by: zhangjs 
Signed-off-by: Theodore Ts'o 
Reviewed-by: Jan Kara

ext4: enforce the immutable flag on open files

2019-06-10T02:04:33+00:00

According to the chattr man page, "a file with the 'i' attribute
cannot be modified..."  Historically, this was only enforced when the
file was opened, per the rest of the description, "... and the file
can not be opened in write mode".

There is general agreement that we should standardize all file systems
to prevent modifications even for files that were opened at the time
the immutable flag is set.  Eventually, a change to enforce this at
the VFS layer should be landing in mainline.  Until then, enforce this
at the ext4 level to prevent xfstests generic/553 from failing.

Signed-off-by: Theodore Ts'o 
Cc: "Darrick J. Wong" 
Cc: stable@kernel.org

ext4: gracefully handle ext4_break_layouts() failure during truncate

2019-05-30T15:56:23+00:00

ext4_break_layouts() may fail e.g. due to a signal being delivered.
Thus we need to handle its failure gracefully and not by taking the
filesystem down. Currently ext4_break_layouts() failure is rare but it
may become more common once RDMA uses layout leases for handling
long-term page pins for DAX mappings.

To handle the failure we need to move ext4_break_layouts() earlier
during setattr handling before we do hard to undo changes such as
modifying inode size. To be able to do that we also have to move some
other checks which are better done without holding i_mmap_sem earlier.

Reported-and-tested-by: Ira Weiny 
Reviewed-by: Ira Weiny 
Signed-off-by: Jan Kara 
Signed-off-by: Theodore Ts'o

ext4: decrypt only the needed block in __ext4_block_zero_page_range()

2019-05-28T17:27:53+00:00

In __ext4_block_zero_page_range(), only decrypt the block that actually
needs to be decrypted, rather than assuming blocksize == PAGE_SIZE and
decrypting the whole page.

This is in preparation for allowing encryption on ext4 filesystems with
blocksize != PAGE_SIZE.

Signed-off-by: Chandan Rajendra 
(EB: rebase onto previous changes, improve the commit message, and use
 bh_offset())
Signed-off-by: Eric Biggers

ext4: decrypt only the needed blocks in ext4_block_write_begin()

2019-05-28T17:27:53+00:00

In ext4_block_write_begin(), only decrypt the blocks that actually need
to be decrypted (up to two blocks which intersect the boundaries of the
region that will be written to), rather than assuming blocksize ==
PAGE_SIZE and decrypting the whole page.

This is in preparation for allowing encryption on ext4 filesystems with
blocksize != PAGE_SIZE.

Signed-off-by: Chandan Rajendra 
(EB: rebase onto previous changes, improve the commit message,
 and move the check for encrypted inode)
Signed-off-by: Eric Biggers

ext4: clear BH_Uptodate flag on decryption error

2019-05-28T17:27:53+00:00

If decryption fails, ext4_block_write_begin() can return with the page's
buffer_head marked with the BH_Uptodate flag.  This commit clears the
BH_Uptodate flag in such cases.

Signed-off-by: Chandan Rajendra 
Signed-off-by: Eric Biggers

fscrypt: support decrypting multiple filesystem blocks per page

2019-05-28T17:27:53+00:00

Rename fscrypt_decrypt_page() to fscrypt_decrypt_pagecache_blocks() and
redefine its behavior to decrypt all filesystem blocks in the given
region of the given page, rather than assuming that the region consists
of just one filesystem block.  Also remove the 'inode' and 'lblk_num'
parameters, since they can be retrieved from the page as it's already
assumed to be a pagecache page.

This is in preparation for allowing encryption on ext4 filesystems with
blocksize != PAGE_SIZE.

This is based on work by Chandan Rajendra.

Reviewed-by: Chandan Rajendra 
Signed-off-by: Eric Biggers