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Merge tag 'vfs-6.11.iomap' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

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Pull iomap updates from Christian Brauner:
 "This contains some minor work for the iomap subsystem:

   - Add documentation on the design of iomap and how to port to it

   - Optimize iomap_read_folio()

   - Bring back the change to iomap_write_end() to no increase i_size.

     This is accompanied by a change to xfs to reserve blocks for
     truncating large realtime inodes to avoid exposing stale data when
     iomap_write_end() stops increasing i_size"

* tag 'vfs-6.11.iomap' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  iomap: don't increase i_size in iomap_write_end()
  xfs: reserve blocks for truncating large realtime inode
  Documentation: the design of iomap and how to port
  iomap: Optimize iomap_read_folio
This commit is contained in:
Linus Torvalds
2024-07-15 13:28:14 -07:00
parent 98f3a9a4fd 602f09f402
commit 4f5e249ec0
8 changed files with 1352 additions and 27 deletions
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1
Documentation/filesystems/index.rst
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@@ -34,6 +34,7 @@ algorithms work.
seq_file
sharedsubtree
idmappings
iomap/index
automount-support

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.. SPDX-License-Identifier: GPL-2.0
.. _iomap_design:
..
Dumb style notes to maintain the author's sanity:
Please try to start sentences on separate lines so that
sentence changes don't bleed colors in diff.
Heading decorations are documented in sphinx.rst.
==============
Library Design
==============
.. contents:: Table of Contents
:local:
Introduction
============
iomap is a filesystem library for handling common file operations.
The library has two layers:
1. A lower layer that provides an iterator over ranges of file offsets.
This layer tries to obtain mappings of each file ranges to storage
from the filesystem, but the storage information is not necessarily
required.
2. An upper layer that acts upon the space mappings provided by the
lower layer iterator.
The iteration can involve mappings of file's logical offset ranges to
physical extents, but the storage layer information is not necessarily
required, e.g. for walking cached file information.
The library exports various APIs for implementing file operations such
as:
* Pagecache reads and writes
* Folio write faults to the pagecache
* Writeback of dirty folios
* Direct I/O reads and writes
* fsdax I/O reads, writes, loads, and stores
* FIEMAP
* lseek ``SEEK_DATA`` and ``SEEK_HOLE``
* swapfile activation
This origins of this library is the file I/O path that XFS once used; it
has now been extended to cover several other operations.
Who Should Read This?
=====================
The target audience for this document are filesystem, storage, and
pagecache programmers and code reviewers.
If you are working on PCI, machine architectures, or device drivers, you
are most likely in the wrong place.
How Is This Better?
===================
Unlike the classic Linux I/O model which breaks file I/O into small
units (generally memory pages or blocks) and looks up space mappings on
the basis of that unit, the iomap model asks the filesystem for the
largest space mappings that it can create for a given file operation and
initiates operations on that basis.
This strategy improves the filesystem's visibility into the size of the
operation being performed, which enables it to combat fragmentation with
larger space allocations when possible.
Larger space mappings improve runtime performance by amortizing the cost
of mapping function calls into the filesystem across a larger amount of
data.
At a high level, an iomap operation `looks like this
<https://lore.kernel.org/all/ZGbVaewzcCysclPt@dread.disaster.area/>`_:
1. For each byte in the operation range...
1. Obtain a space mapping via ``->iomap_begin``
2. For each sub-unit of work...
1. Revalidate the mapping and go back to (1) above, if necessary.
So far only the pagecache operations need to do this.
2. Do the work
3. Increment operation cursor
4. Release the mapping via ``->iomap_end``, if necessary
Each iomap operation will be covered in more detail below.
This library was covered previously by an `LWN article
<https://lwn.net/Articles/935934/>`_ and a `KernelNewbies page
<https://kernelnewbies.org/KernelProjects/iomap>`_.
The goal of this document is to provide a brief discussion of the
design and capabilities of iomap, followed by a more detailed catalog
of the interfaces presented by iomap.
If you change iomap, please update this design document.
File Range Iterator
===================
Definitions
-----------
* **buffer head**: Shattered remnants of the old buffer cache.
* ``fsblock``: The block size of a file, also known as ``i_blocksize``.
* ``i_rwsem``: The VFS ``struct inode`` rwsemaphore.
Processes hold this in shared mode to read file state and contents.
Some filesystems may allow shared mode for writes.
Processes often hold this in exclusive mode to change file state and
contents.
* ``invalidate_lock``: The pagecache ``struct address_space``
rwsemaphore that protects against folio insertion and removal for
filesystems that support punching out folios below EOF.
Processes wishing to insert folios must hold this lock in shared
mode to prevent removal, though concurrent insertion is allowed.
Processes wishing to remove folios must hold this lock in exclusive
mode to prevent insertions.
Concurrent removals are not allowed.
* ``dax_read_lock``: The RCU read lock that dax takes to prevent a
device pre-shutdown hook from returning before other threads have
released resources.
* **filesystem mapping lock**: This synchronization primitive is
internal to the filesystem and must protect the file mapping data
from updates while a mapping is being sampled.
The filesystem author must determine how this coordination should
happen; it does not need to be an actual lock.
* **iomap internal operation lock**: This is a general term for
synchronization primitives that iomap functions take while holding a
mapping.
A specific example would be taking the folio lock while reading or
writing the pagecache.
* **pure overwrite**: A write operation that does not require any
metadata or zeroing operations to perform during either submission
or completion.
This implies that the fileystem must have already allocated space
on disk as ``IOMAP_MAPPED`` and the filesystem must not place any
constaints on IO alignment or size.
The only constraints on I/O alignment are device level (minimum I/O
size and alignment, typically sector size).
``struct iomap``
----------------
The filesystem communicates to the iomap iterator the mapping of
byte ranges of a file to byte ranges of a storage device with the
structure below:
.. code-block:: c
struct iomap {
u64 addr;
loff_t offset;
u64 length;
u16 type;
u16 flags;
struct block_device *bdev;
struct dax_device *dax_dev;
voidw *inline_data;
void *private;
const struct iomap_folio_ops *folio_ops;
u64 validity_cookie;
};
The fields are as follows:
* ``offset`` and ``length`` describe the range of file offsets, in
bytes, covered by this mapping.
These fields must always be set by the filesystem.
* ``type`` describes the type of the space mapping:
* **IOMAP_HOLE**: No storage has been allocated.
This type must never be returned in response to an ``IOMAP_WRITE``
operation because writes must allocate and map space, and return
the mapping.
The ``addr`` field must be set to ``IOMAP_NULL_ADDR``.
iomap does not support writing (whether via pagecache or direct
I/O) to a hole.
* **IOMAP_DELALLOC**: A promise to allocate space at a later time
("delayed allocation").
If the filesystem returns IOMAP_F_NEW here and the write fails, the
``->iomap_end`` function must delete the reservation.
The ``addr`` field must be set to ``IOMAP_NULL_ADDR``.
* **IOMAP_MAPPED**: The file range maps to specific space on the
storage device.
The device is returned in ``bdev`` or ``dax_dev``.
The device address, in bytes, is returned via ``addr``.
* **IOMAP_UNWRITTEN**: The file range maps to specific space on the
storage device, but the space has not yet been initialized.
The device is returned in ``bdev`` or ``dax_dev``.
The device address, in bytes, is returned via ``addr``.
Reads from this type of mapping will return zeroes to the caller.
For a write or writeback operation, the ioend should update the
mapping to MAPPED.
Refer to the sections about ioends for more details.
* **IOMAP_INLINE**: The file range maps to the memory buffer
specified by ``inline_data``.
For write operation, the ``->iomap_end`` function presumably
handles persisting the data.
The ``addr`` field must be set to ``IOMAP_NULL_ADDR``.
* ``flags`` describe the status of the space mapping.
These flags should be set by the filesystem in ``->iomap_begin``:
* **IOMAP_F_NEW**: The space under the mapping is newly allocated.
Areas that will not be written to must be zeroed.
If a write fails and the mapping is a space reservation, the
reservation must be deleted.
* **IOMAP_F_DIRTY**: The inode will have uncommitted metadata needed
to access any data written.
fdatasync is required to commit these changes to persistent
storage.
This needs to take into account metadata changes that *may* be made
at I/O completion, such as file size updates from direct I/O.
* **IOMAP_F_SHARED**: The space under the mapping is shared.
Copy on write is necessary to avoid corrupting other file data.
* **IOMAP_F_BUFFER_HEAD**: This mapping requires the use of buffer
heads for pagecache operations.
Do not add more uses of this.
* **IOMAP_F_MERGED**: Multiple contiguous block mappings were
coalesced into this single mapping.
This is only useful for FIEMAP.
* **IOMAP_F_XATTR**: The mapping is for extended attribute data, not
regular file data.
This is only useful for FIEMAP.
* **IOMAP_F_PRIVATE**: Starting with this value, the upper bits can
be set by the filesystem for its own purposes.
These flags can be set by iomap itself during file operations.
The filesystem should supply an ``->iomap_end`` function if it needs
to observe these flags:
* **IOMAP_F_SIZE_CHANGED**: The file size has changed as a result of
using this mapping.
* **IOMAP_F_STALE**: The mapping was found to be stale.
iomap will call ``->iomap_end`` on this mapping and then
``->iomap_begin`` to obtain a new mapping.
Currently, these flags are only set by pagecache operations.
* ``addr`` describes the device address, in bytes.
* ``bdev`` describes the block device for this mapping.
This only needs to be set for mapped or unwritten operations.
* ``dax_dev`` describes the DAX device for this mapping.
This only needs to be set for mapped or unwritten operations, and
only for a fsdax operation.
* ``inline_data`` points to a memory buffer for I/O involving
``IOMAP_INLINE`` mappings.
This value is ignored for all other mapping types.
* ``private`` is a pointer to `filesystem-private information
<https://lore.kernel.org/all/20180619164137.13720-7-hch@lst.de/>`_.
This value will be passed unchanged to ``->iomap_end``.
* ``folio_ops`` will be covered in the section on pagecache operations.
* ``validity_cookie`` is a magic freshness value set by the filesystem
that should be used to detect stale mappings.
For pagecache operations this is critical for correct operation
because page faults can occur, which implies that filesystem locks
should not be held between ``->iomap_begin`` and ``->iomap_end``.
Filesystems with completely static mappings need not set this value.
Only pagecache operations revalidate mappings; see the section about
``iomap_valid`` for details.
``struct iomap_ops``
--------------------
Every iomap function requires the filesystem to pass an operations
structure to obtain a mapping and (optionally) to release the mapping:
.. code-block:: c
struct iomap_ops {
int (*iomap_begin)(struct inode *inode, loff_t pos, loff_t length,
unsigned flags, struct iomap *iomap,
struct iomap *srcmap);
int (*iomap_end)(struct inode *inode, loff_t pos, loff_t length,
ssize_t written, unsigned flags,
struct iomap *iomap);
};
``->iomap_begin``
~~~~~~~~~~~~~~~~~
iomap operations call ``->iomap_begin`` to obtain one file mapping for
the range of bytes specified by ``pos`` and ``length`` for the file
``inode``.
This mapping should be returned through the ``iomap`` pointer.
The mapping must cover at least the first byte of the supplied file
range, but it does not need to cover the entire requested range.
Each iomap operation describes the requested operation through the
``flags`` argument.
The exact value of ``flags`` will be documented in the
operation-specific sections below.
These flags can, at least in principle, apply generally to iomap
operations:
* ``IOMAP_DIRECT`` is set when the caller wishes to issue file I/O to
block storage.
* ``IOMAP_DAX`` is set when the caller wishes to issue file I/O to
memory-like storage.
* ``IOMAP_NOWAIT`` is set when the caller wishes to perform a best
effort attempt to avoid any operation that would result in blocking
the submitting task.
This is similar in intent to ``O_NONBLOCK`` for network APIs - it is
intended for asynchronous applications to keep doing other work
instead of waiting for the specific unavailable filesystem resource
to become available.
Filesystems implementing ``IOMAP_NOWAIT`` semantics need to use
trylock algorithms.
They need to be able to satisfy the entire I/O request range with a
single iomap mapping.
They need to avoid reading or writing metadata synchronously.
They need to avoid blocking memory allocations.
They need to avoid waiting on transaction reservations to allow
modifications to take place.
They probably should not be allocating new space.
And so on.
If there is any doubt in the filesystem developer's mind as to
whether any specific ``IOMAP_NOWAIT`` operation may end up blocking,
then they should return ``-EAGAIN`` as early as possible rather than
start the operation and force the submitting task to block.
``IOMAP_NOWAIT`` is often set on behalf of ``IOCB_NOWAIT`` or
``RWF_NOWAIT``.
If it is necessary to read existing file contents from a `different
<https://lore.kernel.org/all/20191008071527.29304-9-hch@lst.de/>`_
device or address range on a device, the filesystem should return that
information via ``srcmap``.
Only pagecache and fsdax operations support reading from one mapping and
writing to another.
``->iomap_end``
~~~~~~~~~~~~~~~
After the operation completes, the ``->iomap_end`` function, if present,
is called to signal that iomap is finished with a mapping.
Typically, implementations will use this function to tear down any
context that were set up in ``->iomap_begin``.
For example, a write might wish to commit the reservations for the bytes
that were operated upon and unreserve any space that was not operated
upon.
``written`` might be zero if no bytes were touched.
``flags`` will contain the same value passed to ``->iomap_begin``.
iomap ops for reads are not likely to need to supply this function.
Both functions should return a negative errno code on error, or zero on
success.
Preparing for File Operations
=============================
iomap only handles mapping and I/O.
Filesystems must still call out to the VFS to check input parameters
and file state before initiating an I/O operation.
It does not handle obtaining filesystem freeze protection, updating of
timestamps, stripping privileges, or access control.
Locking Hierarchy
=================
iomap requires that filesystems supply their own locking model.
There are three categories of synchronization primitives, as far as
iomap is concerned:
* The **upper** level primitive is provided by the filesystem to
coordinate access to different iomap operations.
The exact primitive is specifc to the filesystem and operation,
but is often a VFS inode, pagecache invalidation, or folio lock.
For example, a filesystem might take ``i_rwsem`` before calling
``iomap_file_buffered_write`` and ``iomap_file_unshare`` to prevent
these two file operations from clobbering each other.
Pagecache writeback may lock a folio to prevent other threads from
accessing the folio until writeback is underway.
* The **lower** level primitive is taken by the filesystem in the
``->iomap_begin`` and ``->iomap_end`` functions to coordinate
access to the file space mapping information.
The fields of the iomap object should be filled out while holding
this primitive.
The upper level synchronization primitive, if any, remains held
while acquiring the lower level synchronization primitive.
For example, XFS takes ``ILOCK_EXCL`` and ext4 takes ``i_data_sem``
while sampling mappings.
Filesystems with immutable mapping information may not require
synchronization here.
* The **operation** primitive is taken by an iomap operation to
coordinate access to its own internal data structures.
The upper level synchronization primitive, if any, remains held
while acquiring this primitive.
The lower level primitive is not held while acquiring this
primitive.
For example, pagecache write operations will obtain a file mapping,
then grab and lock a folio to copy new contents.
It may also lock an internal folio state object to update metadata.
The exact locking requirements are specific to the filesystem; for
certain operations, some of these locks can be elided.
All further mention of locking are *recommendations*, not mandates.
Each filesystem author must figure out the locking for themself.
Bugs and Limitations
====================
* No support for fscrypt.
* No support for compression.
* No support for fsverity yet.
* Strong assumptions that IO should work the way it does on XFS.
* Does iomap *actually* work for non-regular file data?
Patches welcome!

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@@ -0,0 +1,13 @@
.. SPDX-License-Identifier: GPL-2.0
=======================
VFS iomap Documentation
=======================
.. toctree::
:maxdepth: 2
:numbered:
design
operations
porting

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@@ -0,0 +1,120 @@
.. SPDX-License-Identifier: GPL-2.0
.. _iomap_porting:
..
Dumb style notes to maintain the author's sanity:
Please try to start sentences on separate lines so that
sentence changes don't bleed colors in diff.
Heading decorations are documented in sphinx.rst.
=======================
Porting Your Filesystem
=======================
.. contents:: Table of Contents
:local:
Why Convert?
============
There are several reasons to convert a filesystem to iomap:
1. The classic Linux I/O path is not terribly efficient.
Pagecache operations lock a single base page at a time and then call
into the filesystem to return a mapping for only that page.
Direct I/O operations build I/O requests a single file block at a
time.
This worked well enough for direct/indirect-mapped filesystems such
as ext2, but is very inefficient for extent-based filesystems such
as XFS.
2. Large folios are only supported via iomap; there are no plans to
convert the old buffer_head path to use them.
3. Direct access to storage on memory-like devices (fsdax) is only
supported via iomap.
4. Lower maintenance overhead for individual filesystem maintainers.
iomap handles common pagecache related operations itself, such as
allocating, instantiating, locking, and unlocking of folios.
No ->write_begin(), ->write_end() or direct_IO
address_space_operations are required to be implemented by
filesystem using iomap.
How Do I Convert a Filesystem?
==============================
First, add ``#include <linux/iomap.h>`` from your source code and add
``select FS_IOMAP`` to your filesystem's Kconfig option.
Build the kernel, run fstests with the ``-g all`` option across a wide
variety of your filesystem's supported configurations to build a
baseline of which tests pass and which ones fail.
The recommended approach is first to implement ``->iomap_begin`` (and
``->iomap_end`` if necessary) to allow iomap to obtain a read-only
mapping of a file range.
In most cases, this is a relatively trivial conversion of the existing
``get_block()`` function for read-only mappings.
``FS_IOC_FIEMAP`` is a good first target because it is trivial to
implement support for it and then to determine that the extent map
iteration is correct from userspace.
If FIEMAP is returning the correct information, it's a good sign that
other read-only mapping operations will do the right thing.
Next, modify the filesystem's ``get_block(create = false)``
implementation to use the new ``->iomap_begin`` implementation to map
file space for selected read operations.
Hide behind a debugging knob the ability to switch on the iomap mapping
functions for selected call paths.
It is necessary to write some code to fill out the bufferhead-based
mapping information from the ``iomap`` structure, but the new functions
can be tested without needing to implement any iomap APIs.
Once the read-only functions are working like this, convert each high
level file operation one by one to use iomap native APIs instead of
going through ``get_block()``.
Done one at a time, regressions should be self evident.
You *do* have a regression test baseline for fstests, right?
It is suggested to convert swap file activation, ``SEEK_DATA``, and
``SEEK_HOLE`` before tackling the I/O paths.
A likely complexity at this point will be converting the buffered read
I/O path because of bufferheads.
The buffered read I/O paths doesn't need to be converted yet, though the
direct I/O read path should be converted in this phase.
At this point, you should look over your ``->iomap_begin`` function.
If it switches between large blocks of code based on dispatching of the
``flags`` argument, you should consider breaking it up into
per-operation iomap ops with smaller, more cohesive functions.
XFS is a good example of this.
The next thing to do is implement ``get_blocks(create == true)``
functionality in the ``->iomap_begin``/``->iomap_end`` methods.
It is strongly recommended to create separate mapping functions and
iomap ops for write operations.
Then convert the direct I/O write path to iomap, and start running fsx
w/ DIO enabled in earnest on filesystem.
This will flush out lots of data integrity corner case bugs that the new
write mapping implementation introduces.
Now, convert any remaining file operations to call the iomap functions.
This will get the entire filesystem using the new mapping functions, and
they should largely be debugged and working correctly after this step.
Most likely at this point, the buffered read and write paths will still
need to be converted.
The mapping functions should all work correctly, so all that needs to be
done is rewriting all the code that interfaces with bufferheads to
interface with iomap and folios.
It is much easier first to get regular file I/O (without any fancy
features like fscrypt, fsverity, compression, or data=journaling)
converted to use iomap.
Some of those fancy features (fscrypt and compression) aren't
implemented yet in iomap.
For unjournalled filesystems that use the pagecache for symbolic links
and directories, you might also try converting their handling to iomap.
The rest is left as an exercise for the reader, as it will be different
for every filesystem.
If you encounter problems, email the people and lists in
``get_maintainers.pl`` for help.

1
MAINTAINERS
View File

@@ -8460,6 +8460,7 @@ R: Darrick J. Wong <djwong@kernel.org>
L: linux-xfs@vger.kernel.org
L: linux-fsdevel@vger.kernel.org
S: Supported
F: Documentation/filesystems/iomap/*
F: fs/iomap/
F: include/linux/iomap.h

75
fs/iomap/buffered-io.c
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@@ -442,6 +442,24 @@ done:
return pos - orig_pos + plen;
}
static loff_t iomap_read_folio_iter(const struct iomap_iter *iter,
struct iomap_readpage_ctx *ctx)
{
struct folio *folio = ctx->cur_folio;
size_t offset = offset_in_folio(folio, iter->pos);
loff_t length = min_t(loff_t, folio_size(folio) - offset,
iomap_length(iter));
loff_t done, ret;
for (done = 0; done < length; done += ret) {
ret = iomap_readpage_iter(iter, ctx, done);
if (ret <= 0)
return ret;
}
return done;
}
int iomap_read_folio(struct folio *folio, const struct iomap_ops *ops)
{
struct iomap_iter iter = {
@@ -457,7 +475,7 @@ int iomap_read_folio(struct folio *folio, const struct iomap_ops *ops)
trace_iomap_readpage(iter.inode, 1);
while ((ret = iomap_iter(&iter, ops)) > 0)
iter.processed = iomap_readpage_iter(&iter, &ctx, 0);
iter.processed = iomap_read_folio_iter(&iter, &ctx);
if (ctx.bio) {
submit_bio(ctx.bio);
@@ -872,37 +890,22 @@ static bool iomap_write_end(struct iomap_iter *iter, loff_t pos, size_t len,
size_t copied, struct folio *folio)
{
const struct iomap *srcmap = iomap_iter_srcmap(iter);
loff_t old_size = iter->inode->i_size;
size_t written;
if (srcmap->type == IOMAP_INLINE) {
iomap_write_end_inline(iter, folio, pos, copied);
written = copied;
} else if (srcmap->flags & IOMAP_F_BUFFER_HEAD) {
written = block_write_end(NULL, iter->inode->i_mapping, pos,
return true;
}
if (srcmap->flags & IOMAP_F_BUFFER_HEAD) {
size_t bh_written;
bh_written = block_write_end(NULL, iter->inode->i_mapping, pos,
len, copied, &folio->page, NULL);
WARN_ON_ONCE(written != copied && written != 0);
} else {
written = __iomap_write_end(iter->inode, pos, len, copied,
folio) ? copied : 0;
WARN_ON_ONCE(bh_written != copied && bh_written != 0);
return bh_written == copied;
}
/*
* Update the in-memory inode size after copying the data into the page
* cache. It's up to the file system to write the updated size to disk,
* preferably after I/O completion so that no stale data is exposed.
* Only once that's done can we unlock and release the folio.
*/
if (pos + written > old_size) {
i_size_write(iter->inode, pos + written);
iter->iomap.flags |= IOMAP_F_SIZE_CHANGED;
}
__iomap_put_folio(iter, pos, written, folio);
if (old_size < pos)
pagecache_isize_extended(iter->inode, old_size, pos);
return written == copied;
return __iomap_write_end(iter->inode, pos, len, copied, folio);
}
static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i)
@@ -917,6 +920,7 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i)
do {
struct folio *folio;
loff_t old_size;
size_t offset; /* Offset into folio */
size_t bytes; /* Bytes to write to folio */
size_t copied; /* Bytes copied from user */
@@ -968,6 +972,23 @@ retry:
written = iomap_write_end(iter, pos, bytes, copied, folio) ?
copied : 0;
/*
* Update the in-memory inode size after copying the data into
* the page cache. It's up to the file system to write the
* updated size to disk, preferably after I/O completion so that
* no stale data is exposed. Only once that's done can we
* unlock and release the folio.
*/
old_size = iter->inode->i_size;
if (pos + written > old_size) {
i_size_write(iter->inode, pos + written);
iter->iomap.flags |= IOMAP_F_SIZE_CHANGED;
}
__iomap_put_folio(iter, pos, written, folio);
if (old_size < pos)
pagecache_isize_extended(iter->inode, old_size, pos);
cond_resched();
if (unlikely(written == 0)) {
/*
@@ -1338,6 +1359,7 @@ static loff_t iomap_unshare_iter(struct iomap_iter *iter)
bytes = folio_size(folio) - offset;
ret = iomap_write_end(iter, pos, bytes, bytes, folio);
__iomap_put_folio(iter, pos, bytes, folio);
if (WARN_ON_ONCE(!ret))
return -EIO;
@@ -1403,6 +1425,7 @@ static loff_t iomap_zero_iter(struct iomap_iter *iter, bool *did_zero)
folio_mark_accessed(folio);
ret = iomap_write_end(iter, pos, bytes, bytes, folio);
__iomap_put_folio(iter, pos, bytes, folio);
if (WARN_ON_ONCE(!ret))
return -EIO;

15
fs/xfs/xfs_iops.c
View File

@@ -17,6 +17,8 @@
#include "xfs_da_btree.h"
#include "xfs_attr.h"
#include "xfs_trans.h"
#include "xfs_trans_space.h"
#include "xfs_bmap_btree.h"
#include "xfs_trace.h"
#include "xfs_icache.h"
#include "xfs_symlink.h"
@@ -811,6 +813,7 @@ xfs_setattr_size(
struct xfs_trans *tp;
int error;
uint lock_flags = 0;
uint resblks = 0;
bool did_zeroing = false;
xfs_assert_ilocked(ip, XFS_IOLOCK_EXCL | XFS_MMAPLOCK_EXCL);
@@ -917,7 +920,17 @@ xfs_setattr_size(
return error;
}
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, 0, 0, 0, &tp);
/*
* For realtime inode with more than one block rtextsize, we need the
* block reservation for bmap btree block allocations/splits that can
* happen since it could split the tail written extent and convert the
* right beyond EOF one to unwritten.
*/
if (xfs_inode_has_bigrtalloc(ip))
resblks = XFS_DIOSTRAT_SPACE_RES(mp, 0);
error = xfs_trans_alloc(mp, &M_RES(mp)->tr_itruncate, resblks,
0, 0, &tp);
if (error)
return error;