This inserts sanity check that refuses to mount a filesystem with
unsupported block size.

Previously, kernel code of nilfs was looking only limitation of
devices though mkfs.nilfs2 limits the range of block sizes; there was
no check that prevents rec_len overflow with larger block sizes.

With this change, block sizes larger than 64KB or smaller than 1KB
will get rejected explicitly by kernel.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

With 64KB blocksize, a directory entry can have size 64KB which does
not fit into 16 bits we have for entry length.  So this patch stores
0xffff instead and converts value when read from / written to disk.

Nilfs derives its directory implementation from ext2 filesystem, and
this draws upon the corresponding change on ext2.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

Implementation of nilfs_get_page() is a bit old as below:

 - A common read_mapping_page inline function is now available instead
   of its read_cache_page use.
 - wait_on_page_locked() use in the function is eliminable since
   read_cache_page function does the same thing through wait_on_page_read().
 - PageUptodate() check is eliminable for the same reason.

This renews nilfs_get_page() based on these points.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

This forces nilfs to check compatibility of feature flags so as to
reject a filesystem with unknown features when it mounts or remounts
the filesystem.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

This adds three new fields to nilfs_super_block structure, compatible
feature set, readonly-compatible feature set, and incompatible feature
set in order to prepare for future disk format modifications.

The role of these fields conforms to those of ext3 or other
filesystems.  Most important flags are the incompatible feature set;
it is used to refuse to mount the filesystem which sets an
incompatible feature the kernel doesn't know about.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

This inserts comments indicating hexadecimal offset in declaration of
nilfs_super_block structure so that people can know offset of its
fields without counting from the head.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

This applies read-ahead to nilfs_btree_do_lookup and
nilfs_btree_lookup_contig functions and extends them to read ahead
siblings of level 1 btree nodes that hold data blocks.

At present, the read-ahead is not applied to most btree operations;
only get_block() callback function, which is used during read of
regular files or directories, receives the benefit.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs_btree_get_block() now may return untested buffer due to
read-ahead.  This adds a new flag for buffer heads so that the btree
code can check whether the buffer is already verified or not.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

This adds __nilfs_btree_get_block() function that can issue a series
of read-ahead requests for sibling btree nodes.

This read-ahead needs parent node block, so nilfs_btree_readahead_info
structure is added to pass the information that
__nilfs_btree_get_block() needs.

This also replaces the previous nilfs_btree_get_block() implementation
with a wrapper function of __nilfs_btree_get_block().
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

This adds mode argument to nilfs_btnode_submit_block() function and
allows it to issue a read-ahead request.

An optional submit_ptr argument is also added to store the actual
block address for which bio is sent.  submit_ptr is used for a series
of read-ahead requests, and helps to decide if each requested block is
continous to the previous one on disk.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs_btnode_submit_block() refers to buffer head just before
returning from the function, but it releases the buffer head earlier
than that if nilfs_dat_translate() gets an error.

This has potential for oops in the erroneous case.  This fixes the
issue.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

This removes all inline uses from btree.c.  Gcc now agressively apply
inline expansion even for the functions declared without the keyword;
the inline use in btree.c looks excessive.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

The patch "reduce repetitive calculation of max number of child nodes"
gathered up the calculation of maximum number of child nodes into
nilfs_btree_nchildren_per_block() function.  This makes the function
get resultant value from a private variable in bmap object instead of
calculating it for each call.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

The current btree implementation repeats the same calculation on the
maximum number of child nodes.  This is because a few low level
routines use the calculation for index addressing in a btree node
block.

This reduces the calculation by explicitly passing the maximum number
of child nodes (ncmax) through their argument.

This changes parameter passing of the following functions:

 - nilfs_btree_node_dptrs
 - nilfs_btree_node_get_ptr
 - nilfs_btree_node_set_ptr
 - nilfs_btree_node_init
 - nilfs_btree_node_move_left
 - nilfs_btree_node_move_right
 - nilfs_btree_node_insert
 - nilfs_btree_node_delete, and
 - nilfs_btree_get_node

The following functions are removed:

 - nilfs_btree_node_nchildren_min
 - nilfs_btree_node_nchildren_max

Most middle level btree operations are rewritten to pass a proper
ncmax value depending on whether each occurrence of node is "root" or
not.

A constant NILFS_BTREE_ROOT_NCHILDREN_MAX is used for the root node,
whereas nilfs_btree_nchildren_per_block() function is used for
non-root nodes.  If a node could be either root or a non-root node, an
output argument of nilfs_btree_get_node() is used to set up ncmax.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs_btree_node_nchildren_max() and nilfs_btree_node_nchildren_min()
functions switch return value depending on whether target node is the
root or a node block.  In most uses of these functions, however, the
node type is fixed, and moreover the same calculation is repeatedly
performed in loop.

This unfold these functions depending on context and move them outside
loops wherever possible.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs_bmap_lookup and its variants are supposed to take a valid
pointer argument to return a block address, thus pointer checks in
nilfs_btree_lookup and nilfs_direct_lookup are needless.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

This removes nilfs_bmap_union and finally unifies three structures and
the union in bmap/btree code into one.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

This unifies two similar functions nilfs_btree_set_target_v and
nilfs_direct_set_target_v into one, nilfs_bmap_set_target_v.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

This replaces all uses of nilfs_btree struct in implementation of
btree mapping with nilfs_bmap struct.

Name of local variable "btree" is kept not to bloat amount of change.
And, a part of local variables "bmap" is renamed to "btree" to uniform
naming rule.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

This replaces all uses of nilfs_direct struct in implementation of
direct mapping with nilfs_bmap struct.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

The first argument of bops->bop_propagate operation takes a constant
qualifier, and causes compilation error when removed cast to pointer
of nilfs_btree structure type.  This fixes the issue to prepare for
succesive removal of nilfs_btree struct.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

Will remove nilfs_bmap_key_to_dkey(), nilfs_bmap_dkey_to_key(),
nilfs_bmap_ptr_to_dptr(), and nilfs_bmap_dptr_to_ptr() for simplicity.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

This inserts sanity checks soon after read btree node from disk.  This
allows early detection of broken btree nodes, and helps to narrow down
problems due to file system corruption.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

According to the report titled "problem with nilfs_cleanerd" from
Łukasz Wójcicki, nilfs_btree_lookup_dirty_buffers or
nilfs_btree_add_dirty_buffer got memory violation during garbage
collection.

This could happen if a level field of given btree node buffer is
incorrect, which is a crucial internal bug.

This inserts a sanity check to figure out the problem.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

This adds is_remount argument to the parse_options() function that
obtains mount options from strings.

Previously, parse_options did not distinguish context whether it's
called for a new mount or remount, so the caller needed additional
verifications outside the function.

This allows parse_options to verify options and print messages
depending on the context.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

This replaces seq_printf() with seq_puts() in nilfs_show_options for
mount options which have no argument.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

Nilfs has "discard" mount option which issues discard/TRIM commands to
underlying block device, but it lacks a complementary option and has
no way to disable the feature through remount.

This adds "nodiscard" option to resolve this imbalance.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

Nilfs enables write barriers by default and has "nobarrier" mount
option to disable this feature.  But it lacks the complementary option
and has no way to re-enable the feature on remount.

This adds "barrier" option to resolve this imbalance.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

Super blocks of nilfs are periodically overwritten in order to record
the recent log position.  This shortens recovery time after unclean
unmount, but the current implementation performs the update even for a
few blocks of change.  If the filesystem gets small changes slowly and
continually, super blocks may be updated excessively.

This moderates the issue by skipping update of log cursor if it does
not cross a segment boundary.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

Although nilfs redundantly uses two super blocks and each may point to
different position on log, the current version of nilfs does not try
fallback to the spare super block when it doesn't find any valid log
at the position that the primary super block points to.

This has been a cause of mount failures due to write order reversals
on barrier less block devices.

This inserts fallback code in error path of nilfs_search_super_root
routine to resolve the mount failure problem.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

nilfs_search_super_root can return -ENOMEM, but this error code is not
described in its kernel-doc comment.  This fixes the discrepancy.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

This separates a setup routine of log cursor from init_nilfs().  The
routine, nilfs_store_log_cursor, reads the last position of the log
containing a super root, and initializes relevant state on the nilfs
object.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

This will sync super blocks in turns instead of syncing duplicate
super blocks at the time.  This will help searching valid super root
when super block is written into disk before log is written, which is
happen when barrier-less block devices are unmounted uncleanly.  In
the situation, old super block likely points to valid log.

This patch introduces ns_sbwcount member to the nilfs object and adds
nilfs_sb_will_flip() function; ns_sbwcount counts how many times super
blocks write back to the disk.  And, nilfs_sb_will_flip() decides
whether flipping required or not based on the count of ns_sbwcount to
sync super blocks asymmetrically.

The following functions are also changed:

 - nilfs_prepare_super(): flips super blocks according to the
   argument.  The argument is calculated by nilfs_sb_will_flip()
   function.

 - nilfs_cleanup_super(): sets "clean" flag to both super blocks if
   they point to the same checkpoint.

To update both of super block information, caller of
nilfs_commit_super must set the information on both super blocks.
Signed-off-by: NJiro SEKIBA <jir@unicus.jp>
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

This function checks validity of super block pointers.
If first super block is invalid, it will swap the super blocks.
The function should be called before any super block information updates.
Caller must obtain nilfs->ns_sem.
Signed-off-by: NJiro SEKIBA <jir@unicus.jp>
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

This moves out section that updates information of the recent log
position stored in super blocks from nilfs_commit_super to a new
routine named nilfs_set_log_cursor.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

This function marks error state and write it on super blocks.  This is
a preparation for making super block writeback alternately.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

This function write out filesystem state to super blocks in order to
share the same cleanup work.  This is a preparation for making super
block writeback alternately.

Cc: Jiro SEKIBA <jir@unicus.jp>
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

Mount time field in super block is wrongly updated when nilfs remounts
the partition from read-write to read-only.  This fixes the issue.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

This counter is unused.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

This removes macros to test segment summary flags and redefines a few
relevant macros with inline functions.
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>