f2fs_gc. It was newly introduced in 4.9-rc1.
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1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=1MpQ
-----END PGP SIGNATURE-----
Merge tag 'for-f2fs-4.9-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs
Pull f2fs bugfix from Jaegeuk Kim:
"This fixes a bug which referenced the wrong pointer, sum_page, in
f2fs_gc. It was newly introduced in 4.9-rc1.
* tag 'for-f2fs-4.9-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs:
f2fs: fix wrong sum_page pointer in f2fs_gc
The mapping_set_error() helper sets the correct AS_ flag for the mapping
so there is no reason to open code it. Use the helper directly.
[akpm@linux-foundation.org: be honest about conversion from -ENXIO to -EIO]
Link: http://lkml.kernel.org/r/20160912111608.2588-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull more vfs updates from Al Viro:
">rename2() work from Miklos + current_time() from Deepa"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
fs: Replace current_fs_time() with current_time()
fs: Replace CURRENT_TIME_SEC with current_time() for inode timestamps
fs: Replace CURRENT_TIME with current_time() for inode timestamps
fs: proc: Delete inode time initializations in proc_alloc_inode()
vfs: Add current_time() api
vfs: add note about i_op->rename changes to porting
fs: rename "rename2" i_op to "rename"
vfs: remove unused i_op->rename
fs: make remaining filesystems use .rename2
libfs: support RENAME_NOREPLACE in simple_rename()
fs: support RENAME_NOREPLACE for local filesystems
ncpfs: fix unused variable warning
Pull vfs xattr updates from Al Viro:
"xattr stuff from Andreas
This completes the switch to xattr_handler ->get()/->set() from
->getxattr/->setxattr/->removexattr"
* 'work.xattr' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
vfs: Remove {get,set,remove}xattr inode operations
xattr: Stop calling {get,set,remove}xattr inode operations
vfs: Check for the IOP_XATTR flag in listxattr
xattr: Add __vfs_{get,set,remove}xattr helpers
libfs: Use IOP_XATTR flag for empty directory handling
vfs: Use IOP_XATTR flag for bad-inode handling
vfs: Add IOP_XATTR inode operations flag
vfs: Move xattr_resolve_name to the front of fs/xattr.c
ecryptfs: Switch to generic xattr handlers
sockfs: Get rid of getxattr iop
sockfs: getxattr: Fail with -EOPNOTSUPP for invalid attribute names
kernfs: Switch to generic xattr handlers
hfs: Switch to generic xattr handlers
jffs2: Remove jffs2_{get,set,remove}xattr macros
xattr: Remove unnecessary NULL attribute name check
Pull misc vfs updates from Al Viro:
"Assorted misc bits and pieces.
There are several single-topic branches left after this (rename2
series from Miklos, current_time series from Deepa Dinamani, xattr
series from Andreas, uaccess stuff from from me) and I'd prefer to
send those separately"
* 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (39 commits)
proc: switch auxv to use of __mem_open()
hpfs: support FIEMAP
cifs: get rid of unused arguments of CIFSSMBWrite()
posix_acl: uapi header split
posix_acl: xattr representation cleanups
fs/aio.c: eliminate redundant loads in put_aio_ring_file
fs/internal.h: add const to ns_dentry_operations declaration
compat: remove compat_printk()
fs/buffer.c: make __getblk_slow() static
proc: unsigned file descriptors
fs/file: more unsigned file descriptors
fs: compat: remove redundant check of nr_segs
cachefiles: Fix attempt to read i_blocks after deleting file [ver #2]
cifs: don't use memcpy() to copy struct iov_iter
get rid of separate multipage fault-in primitives
fs: Avoid premature clearing of capabilities
fs: Give dentry to inode_change_ok() instead of inode
fuse: Propagate dentry down to inode_change_ok()
ceph: Propagate dentry down to inode_change_ok()
xfs: Propagate dentry down to inode_change_ok()
...
These inode operations are no longer used; remove them.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-----BEGIN PGP SIGNATURE-----
iQEcBAABCAAGBQJX9pA6AAoJEPL5WVaVDYGj7fwH/0YcdQWBg0O5d7iXFnTcimh9
fiYkqKniBWQhgBAOFPMoNPRIW4tyeQmTtu8Rywx2Hr+v4lzJvuOaT18NDANdq/pp
u5eDrnJ4R+uqPJlgxVOzopLVJ6I2glgSSRdvAKYxwTYcv8F88ObzVfsJ4M415gPq
cbEKF+JT3l5hTGENR5sqmYvHYaNfOFkOqt4gulPtgk1eshy+BH/05M+qBSeA5a6k
srdon0pFRoUV68m+T4G8FqOZxdybeT5Yx6X0GJf0eQJoX7IaiQTPcDrXzlrbDBbN
rrzbpwsDeDKtgSOckbarCBroZKdToHFekfnOJ7IPWYq8IwYTSnZKFCWIRKO6z38=
=IvhS
-----END PGP SIGNATURE-----
Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4
Pull ext4 updates from Ted Ts'o:
"Lots of bug fixes and cleanups"
* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (40 commits)
ext4: remove unused variable
ext4: use journal inode to determine journal overhead
ext4: create function to read journal inode
ext4: unmap metadata when zeroing blocks
ext4: remove plugging from ext4_file_write_iter()
ext4: allow unlocked direct IO when pages are cached
ext4: require encryption feature for EXT4_IOC_SET_ENCRYPTION_POLICY
fscrypto: use standard macros to compute length of fname ciphertext
ext4: do not unnecessarily null-terminate encrypted symlink data
ext4: release bh in make_indexed_dir
ext4: Allow parallel DIO reads
ext4: allow DAX writeback for hole punch
jbd2: fix lockdep annotation in add_transaction_credits()
blockgroup_lock.h: simplify definition of NR_BG_LOCKS
blockgroup_lock.h: remove debris from bgl_lock_ptr() conversion
fscrypto: make filename crypto functions return 0 on success
fscrypto: rename completion callbacks to reflect usage
fscrypto: remove unnecessary includes
fscrypto: improved validation when loading inode encryption metadata
ext4: fix memory leak when symlink decryption fails
...
injection facility. With this, we could fix several corner cases. And, in order
to improve the performance, we set inline_dentry by default and enhance the
exisiting discard issue flow. In addition, we added f2fs_migrate_page for better
memory management.
= Enhancement =
- set inline_dentry by default
- improve discard issue flow
- add more fault injection cases in f2fs
- allow block preallocation for encrypted files
- introduce migrate_page callback function
- avoid truncating the next direct node block at every checkpoint
= Bug fixes =
- set page flag correctly between write_begin and write_end
- missing error handling cases detected by fault injection
- preallocate blocks regarding to 4KB alignement correctly
- dentry and filename handling of encryption
- lost xattrs of directories
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1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=crpN
-----END PGP SIGNATURE-----
Merge tag 'for-f2fs-4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs
Pull f2fs updates from Jaegeuk Kim:
"In this round, we've investigated how f2fs deals with errors given by
our fault injection facility. With this, we could fix several corner
cases. And, in order to improve the performance, we set inline_dentry
by default and enhance the exisiting discard issue flow. In addition,
we added f2fs_migrate_page for better memory management.
Enhancements:
- set inline_dentry by default
- improve discard issue flow
- add more fault injection cases in f2fs
- allow block preallocation for encrypted files
- introduce migrate_page callback function
- avoid truncating the next direct node block at every checkpoint
Bug fixes:
- set page flag correctly between write_begin and write_end
- missing error handling cases detected by fault injection
- preallocate blocks regarding to 4KB alignement correctly
- dentry and filename handling of encryption
- lost xattrs of directories"
* tag 'for-f2fs-4.9' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs: (69 commits)
f2fs: introduce update_ckpt_flags to clean up
f2fs: don't submit irrelevant page
f2fs: fix to commit bio cache after flushing node pages
f2fs: introduce get_checkpoint_version for cleanup
f2fs: remove dead variable
f2fs: remove redundant io plug
f2fs: support checkpoint error injection
f2fs: fix to recover old fault injection config in ->remount_fs
f2fs: do fault injection initialization in default_options
f2fs: remove redundant value definition
f2fs: support configuring fault injection per superblock
f2fs: adjust display format of segment bit
f2fs: remove dirty inode pages in error path
f2fs: do not unnecessarily null-terminate encrypted symlink data
f2fs: handle errors during recover_orphan_inodes
f2fs: avoid gc in cp_error case
f2fs: should put_page for summary page
f2fs: assign return value in f2fs_gc
f2fs: add customized migrate_page callback
f2fs: introduce cp_lock to protect updating of ckpt_flags
...
While we call ->writepages, there are two cases:
a. we didn't writeout any dirty pages, since they are writebacked by other
thread concurrently.
b. we writeout dirty pages, and have already submitted bio to block layer.
In these cases, we don't need to do additional bio flushing unnecessarily,
it may split bio in cache into smaller one.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
In sync_node_pages, we won't check and commit last merged pages in private
bio cache of f2fs, as these pages were taged as writeback, someone who is
waiting for writebacking of the page will be blocked until the cache was
committed by someone else.
We need to commit node type bio cache to avoid potential deadlock or long
delay of waiting writeback.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
There exists almost same codes when get the value of pre_version
and cur_version in function validate_checkpoint, this patch adds
get_checkpoint_version to clean up redundant codes.
Signed-off-by: Tiezhu Yang <kernelpatch@126.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch adds to support checkpoint error injection in f2fs for testing
fatal error tolerance, it will be useful that it can simulate abnormal
power off by f2fs itself instead of calling godown ioctl by running apps.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
In ->remount_fs, we didn't recover original fault injection config if
we encounter error, fix it.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Do fault injection initialization in default_options to keep consistent
with other default option configurating.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch remove redundant value definition in build_sit_entries
Signed-off-by: Yunlei He <heyunlei@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Previously, we only support global fault injection configuration, so that
when we configure type/rate of fault injection through sysfs, mount
option, it will influence all f2fs partition which is being used.
It is not make sence, since it will be not convenient if developer want
to test separated partitions with different fault injection rate/type
simultaneously, also it's not possible to enable fault injection in one
partition and disable fault injection in other one.
>From now on, we move global configuration of fault injection in module
into per-superblock, hence injection testing can be more flexible.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
When getting EIO while handling orphan inodes, we can get some dirty node
pages. Then, f2fs_write_node_pages() called by iput(node_inode) will try
to flush node pages. But in this case, we should prevent to do that, since
we will try again from the start.
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Null-terminating the fscrypt_symlink_data on read is unnecessary because
it is not string data --- it contains binary ciphertext.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Otherwise, we can hit
f2fs_bug_on(sbi, !PageUptodate(sum_page));
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
We should call put_page for preloaded summary pages in do_garbage_collect.
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch adds a return value of write_checkpoint for f2fs_gc.
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch improves the migration of dirty pages and allows migrating atomic
written pages that F2FS uses in Page Cache. Instead of the fallback releasing
page path, it provides better performance for memory compaction, CMA and other
users of memory page migrating. For dirty pages, there is no need to write back
first when migrating. For an atomic written page before committing, we can
migrate the page and update the related 'inmem_pages' list at the same time.
Signed-off-by: Weichao Guo <guoweichao@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
[Jaegeuk Kim: fix some coding style]
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch introduces spinlock to protect updating process of ckpt_flags
field in struct f2fs_checkpoint, it avoids incorrectly updating in race
condition.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
[Jaegeuk Kim: add __is_set_ckpt_flags likewise __set_ckpt_flags]
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Making updating of sbi flag atomic by using {test,set,clear}_bit,
otherwise in concurrency scenario, the flag could be updated incorrectly.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Previously, we used cp_version only to detect recoverable dnodes.
In order to avoid same garbage cp_version, we needed to truncate the next
dnode during checkpoint, resulting in additional discard or data write.
If we can distinguish this by using crc in addition to cp_version, we can
remove this overhead.
There is backward compatibility concern where it changes node_footer layout.
So, this patch introduces a new checkpoint flag, CP_CRC_RECOVERY_FLAG, to
detect new layout. New layout will be activated only when this flag is set.
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
current_fs_time() uses struct super_block* as an argument.
As per Linus's suggestion, this is changed to take struct
inode* as a parameter instead. This is because the function
is primarily meant for vfs inode timestamps.
Also the function was renamed as per Arnd's suggestion.
Change all calls to current_fs_time() to use the new
current_time() function instead. current_fs_time() will be
deleted.
Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
CURRENT_TIME macro is not appropriate for filesystems as it
doesn't use the right granularity for filesystem timestamps.
Use current_time() instead.
CURRENT_TIME is also not y2038 safe.
This is also in preparation for the patch that transitions
vfs timestamps to use 64 bit time and hence make them
y2038 safe. As part of the effort current_time() will be
extended to do range checks. Hence, it is necessary for all
file system timestamps to use current_time(). Also,
current_time() will be transitioned along with vfs to be
y2038 safe.
Note that whenever a single call to current_time() is used
to change timestamps in different inodes, it is because they
share the same time granularity.
Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Felipe Balbi <balbi@kernel.org>
Acked-by: Steven Whitehouse <swhiteho@redhat.com>
Acked-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Acked-by: David Sterba <dsterba@suse.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This patch allow preallocates data blocks for buffered aio writes
in encrypted file.
Signed-off-by: Yunlei He <heyunlei@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
[Jaegeuk Kim: fix to avoid BUG_ON]
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This patch adds to support IO error injection for testing IO error
tolerance of f2fs.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
We treat all error in read_all_xattrs as a no memory error, which covers
the real reason of failure in it. Fix it by return correct errno in order
to reflect the real cause.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
There is no more user of f2fs_filetype_table outside of dir.c, make it
static.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
inode_change_ok() will be resposible for clearing capabilities and IMA
extended attributes and as such will need dentry. Give it as an argument
to inode_change_ok() instead of an inode. Also rename inode_change_ok()
to setattr_prepare() to better relect that it does also some
modifications in addition to checks.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
When file permissions are modified via chmod(2) and the user is not in
the owning group or capable of CAP_FSETID, the setgid bit is cleared in
inode_change_ok(). Setting a POSIX ACL via setxattr(2) sets the file
permissions as well as the new ACL, but doesn't clear the setgid bit in
a similar way; this allows to bypass the check in chmod(2). Fix that.
References: CVE-2016-7097
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Several filename crypto functions: fname_decrypt(),
fscrypt_fname_disk_to_usr(), and fscrypt_fname_usr_to_disk(), returned
the output length on success or -errno on failure. However, the output
length was redundant with the value written to 'oname->len'. It is also
potentially error-prone to make callers have to check for '< 0' instead
of '!= 0'.
Therefore, make these functions return 0 instead of a length, and make
the callers who cared about the return value being a length use
'oname->len' instead. For consistency also make other callers check for
a nonzero result rather than a negative result.
This change also fixes the inconsistency of fname_encrypt() actually
already returning 0 on success, not a length like the other filename
crypto functions and as documented in its function comment.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Acked-by: Jaegeuk Kim <jaegeuk@kernel.org>
The macro f2fs_check_acl is defined but never used since
the initial commit, this patch removes the code that has
been dead for several years.
Signed-off-by: Tiezhu Yang <kernelpatch@126.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
When src and dst is the same file, and the latter part of source region
overlaps with the former part of destination region, current implement
will overwrite data which hasn't been moved yet and truncate data in
overlapped region.
This patch return -EINVAL when such cases occur and return 0 when
source region and destination region is actually the same part of
the same file.
Signed-off-by: Fan li <fanofcode.li@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Previously, f2fs_write_begin sets PageUptodate all the time. But, when user
tries to update the entire page (i.e., len == PAGE_SIZE), we need to consider
that the page is able to be copied partially afterwards. In such the case,
we will lose the remaing region in the page.
This patch fixes this by setting PageUptodate in f2fs_write_end as given copied
result. In the short copy case, it returns zero to let generic_perform_write
retry copying user data again.
As a result, f2fs_write_end() works:
PageUptodate len copied return retry
1. no 4096 4096 4096 false -> return 4096
2. no 4096 1024 0 true -> goto #1 case
3. yes 2048 2048 2048 false -> return 2048
4. yes 2048 1024 1024 false -> return 1024
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>