- 09 Feb, 2021 33 commits
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Naohiro Aota authored
This is 4/4 patch to implement device-replace on zoned filesystems. Even after the copying is done, the write pointers of the source device and the destination device may not be synchronized. For example, when the last allocated extent is freed before device-replace process, the extent is not copied, leaving a hole there. Synchronize the write pointers by writing zeroes to the destination device. Reviewed-by:
Josef Bacik <josef@toxicpanda.com> Signed-off-by:
Naohiro Aota <naohiro.aota@wdc.com> Signed-off-by:
David Sterba <dsterba@suse.com>
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Naohiro Aota authored
This is 3/4 patch to implement device-replace on zoned filesystems. This commit implements copying. To do this, it tracks the write pointer during the device replace process. As device-replace's copy process is smart enough to only copy used extents on the source device, we have to fill the gap to honor the sequential write requirement in the target device. The device-replace process on zoned filesystems must copy or clone all the extents in the source device exactly once. So, we need to ensure allocations started just before the dev-replace process to have their corresponding extent information in the B-trees. finish_extent_writes_for_zoned() implements that functionality, which basically is the removed code in the commit 042528f8 ("Btrfs: fix block group remaining RO forever after error during device replace"). Reviewed-by:
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Naohiro Aota authored
This is 2/4 patch to implement device replace for zoned filesystems. In zoned mode, a block group must be either copied (from the source device to the target device) or cloned (to both devices). Implement the cloning part. If a block group targeted by an IO is marked to copy, we should not clone the IO to the destination device, because the block group is eventually copied by the replace process. This commit also handles cloning of device reset. Reviewed-by:
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Naohiro Aota authored
This is the 1/4 patch to support device-replace on zoned filesystems. We have two types of IOs during the device replace process. One is an IO to "copy" (by the scrub functions) all the device extents from the source device to the destination device. The other one is an IO to "clone" (by handle_ops_on_dev_replace()) new incoming write IOs from users to the source device into the target device. Cloning incoming IOs can break the sequential write rule in on target device. When a write is mapped in the middle of a block group, the IO is directed to the middle of a target device zone, which breaks the sequential write requirement. However, the cloning function cannot be disabled since incoming IOs targeting already copied device extents must be cloned so that the IO is executed on the target device. We cannot use dev_replace->cursor_{left,right} to determine whether a bio is going to a not yet copied region. Since we have a time gap between finishing btrfs_scrub_dev() and rewriting the mapping tree in btrfs_dev_replace_finishing(), we can have a newly allocated device extent which is never cloned nor copied. So the point is to copy only already existing device extents. This patch introduces mark_block_group_to_copy() to mark existing block groups as a target of copying. Then, handle_ops_on_dev_replace() and dev-replace can check the flag to do their job. Also, btrfs_finish_block_group_to_copy() will check if the copied stripe is the last stripe in the block group. With the last stripe copied, the to_copy flag is finally disabled. Afterwards we can safely clone incoming IOs on this block group. Reviewed-by: -
Naohiro Aota authored
On zoned filesystems, btrfs uses per-fs zoned_meta_io_lock to serialize the metadata write IOs. Even with this serialization, write bios sent from btree_write_cache_pages can be reordered by async checksum workers as these workers are per CPU and not per zone. To preserve write bio ordering, we disable async metadata checksum on a zoned filesystem. This does not result in lower performance with HDDs as a single CPU core is fast enough to do checksum for a single zone write stream with the maximum possible bandwidth of the device. If multiple zones are being written simultaneously, HDD seek overhead lowers the achievable maximum bandwidth, resulting again in a per zone checksum serialization not affecting the performance. Reviewed-by:
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Naohiro Aota authored
When truncating a file, file buffers which have already been allocated but not yet written may be truncated. Truncating these buffers could cause breakage of a sequential write pattern in a block group if the truncated blocks are for example followed by blocks allocated to another file. To avoid this problem, always wait for write out of all unwritten buffers before proceeding with the truncate execution. Signed-off-by:
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Naohiro Aota authored
We cannot use zone append for writing metadata, because the B-tree nodes have references to each other using logical address. Without knowing the address in advance, we cannot construct the tree in the first place. So we need to serialize write IOs for metadata. We cannot add a mutex around allocation and submission because metadata blocks are allocated in an earlier stage to build up B-trees. Add a zoned_meta_io_lock and hold it during metadata IO submission in btree_write_cache_pages() to serialize IOs. Furthermore, this adds a per-block group metadata IO submission pointer "meta_write_pointer" to ensure sequential writing, which can break when attempting to write back blocks in an unfinished transaction. If the writing out failed because of a hole and the write out is for data integrity (WB_SYNC_ALL), it returns EAGAIN. A caller like fsync() code should handle this properly e.g. by falling back to a full transaction commit. Reviewed-by:
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Naohiro Aota authored
If more than one IO is issued for one file extent, these IO can be written to separate regions on a device. Since we cannot map one file extent to such a separate area on a zoned filesystem, we need to follow the "one IO == one ordered extent" rule. The normal buffered, uncompressed and not pre-allocated write path (used by cow_file_range()) sometimes does not follow this rule. It can write a part of an ordered extent when specified a region to write e.g., when its called from fdatasync(). Introduce a dedicated (uncompressed buffered) data write path for zoned filesystems, that will COW the region and write it at once. Reviewed-by:
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Naohiro Aota authored
Likewise to buffered IO, enable zone append writing for direct IO when its used on a zoned block device. Reviewed-by:
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Naohiro Aota authored
Enable zone append writing for zoned mode. When using zone append, a bio is issued to the start of a target zone and the device decides to place it inside the zone. Upon completion the device reports the actual written position back to the host. Three parts are necessary to enable zone append mode. First, modify the bio to use REQ_OP_ZONE_APPEND in btrfs_submit_bio_hook() and adjust the bi_sector to point the beginning of the zone. Second, record the returned physical address (and disk/partno) to the ordered extent in end_bio_extent_writepage() after the bio has been completed. We cannot resolve the physical address to the logical address because we can neither take locks nor allocate a buffer in this end_bio context. So, we need to record the physical address to resolve it later in btrfs_finish_ordered_io(). And finally, rewrite the logical addresses of the extent mapping and checksum data according to the physical address using btrfs_rmap_block. If the returned address matches the originally allocated address, we can skip this rewriting process. Reviewed-by:
Johannes Thumshirn <johannes.thumshirn@wdc.com> Signed-off-by:
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Johannes Thumshirn authored
A following patch will add another caller of btrfs_lookup_ordered_extent(), but from a bio's endio context. btrfs_lookup_ordered_extent() uses spin_lock_irq() which unconditionally disables interrupts. Change this to spin_lock_irqsave() so interrupts aren't disabled and re-enabled unconditionally. Reviewed-by:
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Johannes Thumshirn authored
On a zoned filesystem, cache if a block group is on a sequential write only zone. On sequential write only zones, we can use REQ_OP_ZONE_APPEND for writing data, therefore provide btrfs_use_zone_append() to figure out if IO is targeting a sequential write only zone and we can use REQ_OP_ZONE_APPEND for data writing. Reviewed-by:
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Naohiro Aota authored
btrfs_rmap_block currently reverse-maps the physical addresses on all devices to the corresponding logical addresses. Extend the function to match to a specified device. The old functionality of querying all devices is left intact by specifying NULL as target device. A block_device instead of a btrfs_device is passed into btrfs_rmap_block, as this function is intended to reverse-map the result of a bio, which only has a block_device. Also export the function for later use. Reviewed-by:
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Johannes Thumshirn authored
To ensure that an ordered extent maps to a contiguous region on disk, we need to maintain a "one bio == one ordered extent" rule. Ensure that constructing bio does not span more than an ordered extent. Reviewed-by:
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Naohiro Aota authored
For a zone append write, the device decides the location the data is being written to. Therefore we cannot ensure that two bios are written consecutively on the device. In order to ensure that an ordered extent maps to a contiguous region on disk, we need to maintain a "one bio == one ordered extent" rule. Implement splitting of an ordered extent and extent map on bio submission to adhere to the rule. extract_ordered_extent() hooks into btrfs_submit_data_bio() and splits the corresponding ordered extent so that the ordered extent's region fits into one bio and the corresponding device limits. Several sanity checks need to be done in extract_ordered_extent() e.g. - We cannot split once end_bio'd ordered extent because we cannot divide ordered->bytes_left for the split ones - We do not expect a compressed ordered extent - We should not have checksum list because we omit the list splitting. Since the function is called before btrfs_wq_submit_bio() or btrfs_csum_one_bio(), this should be always ensured. We also need to split an extent map by creating a new one. If not, unpin_extent_cache() complains about the difference between the start of the extent map and the file's logical offset. Reviewed-by:
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Naohiro Aota authored
Zoned filesystems use REQ_OP_ZONE_APPEND bios for writing to actual devices. Let btrfs_end_bio() and btrfs_op be aware of it, by mapping REQ_OP_ZONE_APPEND to BTRFS_MAP_WRITE and using btrfs_op() instead of bio_op(). Reviewed-by:
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Naohiro Aota authored
A zoned device has its own hardware restrictions e.g. max_zone_append_size when using REQ_OP_ZONE_APPEND. To follow these restrictions, use bio_add_zone_append_page() instead of bio_add_page(). We need target device to use bio_add_zone_append_page(), so this commit reads the chunk information to cache the target device to btrfs_io_bio(bio)->device. Caching only the target device is sufficient here as zoned filesystems only supports the single profile at the moment. Once more profiles will be supported btrfs_io_bio can hold an extent_map to be able to check for the restrictions of all devices the btrfs_bio will be mapped to. Reviewed-by:
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Naohiro Aota authored
Factor out adding a page to a bio from submit_extent_page(). The page is added only when bio_flags are the same, contiguous and the added page fits in the same stripe as pages in the bio. Condition checks are reordered to allow early return to avoid possibly heavy btrfs_bio_fits_in_stripe() calling. Reviewed-by:
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Naohiro Aota authored
We must reset the zones of a deleted unused block group to rewind the zones' write pointers to the zones' start. To do this, we can use the DISCARD_SYNC code to do the reset when the filesystem is running on zoned devices. Reviewed-by:
Anand Jain <anand.jain@oracle.com> Signed-off-by:
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Naohiro Aota authored
Since the allocation info of a tree log node is not recorded in the extent tree, calculate_alloc_pointer() cannot detect this node, so the pointer can be over a tree node. Replaying the log calls btrfs_remove_free_space() for each node in the log tree. So, advance the pointer after the node to not allocate over it. Reviewed-by:
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Naohiro Aota authored
Tree manipulating operations like merging nodes often release once-allocated tree nodes. Such nodes are cleaned so that pages in the node are not uselessly written out. On zoned volumes, however, such optimization blocks the following IOs as the cancellation of the write out of the freed blocks breaks the sequential write sequence expected by the device. Introduce a list of clean and unwritten extent buffers that have been released in a transaction. Redirty the buffers so that btree_write_cache_pages() can send proper bios to the devices. Besides it clears the entire content of the extent buffer not to confuse raw block scanners e.g. 'btrfs check'. By clearing the content, csum_dirty_buffer() complains about bytenr mismatch, so avoid the checking and checksum using newly introduced buffer flag EXTENT_BUFFER_NO_CHECK. Reviewed-by:
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Naohiro Aota authored
Implement a sequential extent allocator for zoned filesystems. This allocator only needs to check if there is enough space in the block group after the allocation pointer to satisfy the extent allocation request. Therefore the allocator never manages bitmaps or clusters. Also, add assertions to the corresponding functions. As zone append writing is used, it would be unnecessary to track the allocation offset, as the allocator only needs to check available space. But by tracking and returning the offset as an allocated region, we can skip modification of ordered extents and checksum information when there is no IO reordering. Reviewed-by:
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Naohiro Aota authored
In a zoned filesystem a once written then freed region is not usable until the underlying zone has been reset. So we need to distinguish such unusable space from usable free space. Therefore we need to introduce the "zone_unusable" field to the block group structure, and "bytes_zone_unusable" to the space_info structure to track the unusable space. Pinned bytes are always reclaimed to the unusable space. But, when an allocated region is returned before using e.g., the block group becomes read-only between allocation time and reservation time, we can safely return the region to the block group. For the situation, this commit introduces "btrfs_add_free_space_unused". This behaves the same as btrfs_add_free_space() on regular filesystem. On zoned filesystems, it rewinds the allocation offset. Because the read-only bytes tracks free but unusable bytes when the block group is read-only, we need to migrate the zone_unusable bytes to read-only bytes when a block group is marked read-only. Reviewed-by:
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Naohiro Aota authored
Conventional zones do not have a write pointer, so we cannot use it to determine the allocation offset for sequential allocation if a block group contains a conventional zone. But instead, we can consider the end of the highest addressed extent in the block group for the allocation offset. For new block group, we cannot calculate the allocation offset by consulting the extent tree, because it can cause deadlock by taking extent buffer lock after chunk mutex, which is already taken in btrfs_make_block_group(). Since it is a new block group anyways, we can simply set the allocation offset to 0. Reviewed-by:
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Naohiro Aota authored
A zoned filesystem must allocate blocks at the zones' write pointer. The device's write pointer position can be mapped to a logical address within a block group. To facilitate this, add an "alloc_offset" to the block-group to track the logical addresses of the write pointer. This logical address is populated in btrfs_load_block_group_zone_info() from the write pointers of corresponding zones. For now, zoned filesystems the single profile. Supporting non-single profile with zone append writing is not trivial. For example, in the DUP profile, we send a zone append writing IO to two zones on a device. The device reply with written LBAs for the IOs. If the offsets of the returned addresses from the beginning of the zone are different, then it results in different logical addresses. We need fine-grained logical to physical mapping to support such separated physical address issue. Since it should require additional metadata type, disable non-single profiles for now. This commit supports the case all the zones in a block group are sequential. The next patch will handle the case having a conventional zone. Reviewed-by:
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Naohiro Aota authored
Add a check in verify_one_dev_extent() to ensure that a device extent on a zoned block device is aligned to the respective zone boundary. If it isn't, mark the filesystem as unclean. Reviewed-by:
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Naohiro Aota authored
Implement a zoned chunk and device extent allocator. One device zone becomes a device extent so that a zone reset affects only this device extent and does not change the state of blocks in the neighbor device extents. To implement the allocator, we need to extend the following functions for a zoned filesystem. - init_alloc_chunk_ctl - dev_extent_search_start - dev_extent_hole_check - decide_stripe_size init_alloc_chunk_ctl_zoned() is mostly the same as regular one. It always set the stripe_size to the zone size and aligns the parameters to the zone size. dev_extent_search_start() only aligns the start offset to zone boundaries. We don't care about the first 1MB like in regular filesystem because we anyway reserve the first two zones for superblock logging. dev_extent_hole_check_zoned() checks if zones in given hole are either conventional or empty sequential zones. Also, it skips zones reserved for superblock logging. With the change to the hole, the new hole may now contain pending extents. So, in this case, loop again to check that. Finally, decide_stripe_size_zoned() should shrink the number of devices instead of stripe size because we need to honor stripe_size == zone_size. Reviewed-by:
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Johannes Thumshirn authored
Run a zoned filesystem on non-zoned devices. This is done by "slicing up" the block device into static sized chunks and fake a conventional zone on each of them. The emulated zone size is determined from the size of device extent. This is mainly aimed at testing of zoned filesystems, i.e. the zoned chunk allocator, on regular block devices. Reviewed-by:
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Naohiro Aota authored
The implementation of fitrim depends on space cache, which is not used and disabled for zoned extent allocator. So the current code does not work with zoned filesystem. In the future, we can implement fitrim for zoned filesystems by enabling space cache (but, only for fitrim) or scanning the extent tree at fitrim time. For now, disallow fitrim on zoned filesystems. Reviewed-by:
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Johannes Thumshirn authored
Don't set the zoned flag in fs_info as soon as we're encountering the incompat filesystem flag for a zoned filesystem on mount. The zoned flag in fs_info is in a union together with the zone_size, so setting it too early will result in setting an incorrect zone_size as well. Once the correct zone_size is read from the device, we can rely on the zoned flag in fs_info as well to determine if the filesystem is zoned. Reviewed-by:
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Johannes Thumshirn authored
Since we have no write pointer in conventional zones, we cannot determine the allocation offset from it. Instead, we set the allocation offset after the highest addressed extent. This is done by reading the extent tree in btrfs_load_block_group_zone_info(). However, this function is called from btrfs_read_block_groups(), so the read lock for the tree node could be recursively taken. To avoid this unsafe locking scenario, release the path before reading the extent tree to get the allocation offset. Reviewed-by:
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Naohiro Aota authored
A zoned filesystem currently has a superblock at the beginning of the superblock logging zones if the zones are conventional. This difference in superblock position causes a chicken-and-egg problem for filesystems with emulated zones. Since the device is a regular (non-zoned) device, we cannot know if the filesystem is regular or zoned while reading the superblock. But, to load the superblock, we need to see if it is emulated zoned or not. Place the superblocks at the same location as they are on regular filesystem on regular devices to solve the problem. It is possible because it's ensured that all the superblock locations are at an (emulated) conventional zone on regular devices. Reviewed-by:
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Naohiro Aota authored
This is a preparation patch to implement zone emulation on a regular device. To emulate a zoned filesystem on a regular (non-zoned) device, we need to decide an emulated zone size. Instead of making it a compile-time static value, we'll make it configurable at mkfs time. Since we have one zone == one device extent restriction, we can determine the emulated zone size from the size of a device extent. We can extend btrfs_get_dev_zone_info() to show a regular device filled with conventional zones once the zone size is decided. The current call site of btrfs_get_dev_zone_info() during the mount process is earlier than loading the file system trees so that we don't know the size of a device extent at this point. Thus we can't slice a regular device to conventional zones. This patch introduces btrfs_get_dev_zone_info_all_devices to load the zone info for all the devices. And, it places this function in open_ctree() after loading the trees. Reviewed-by:
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- 08 Feb, 2021 7 commits
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Naohiro Aota authored
A ZONE_APPEND bio must follow hardware restrictions (e.g. not exceeding max_zone_append_sectors) not to be split. bio_iov_iter_get_pages builds such restricted bio using __bio_iov_append_get_pages if bio_op(bio) == REQ_OP_ZONE_APPEND. To utilize it, we need to set the bio_op before calling bio_iov_iter_get_pages(). This commit introduces IOMAP_F_ZONE_APPEND, so that iomap user can set the flag to indicate they want REQ_OP_ZONE_APPEND and restricted bio. Reviewed-by:
Darrick J. Wong <darrick.wong@oracle.com> Reviewed-by:
Christoph Hellwig <hch@lst.de> Reviewed-by:
Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Signed-off-by:
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Johannes Thumshirn authored
Add bio_add_zone_append_page(), a wrapper around bio_add_hw_page() which is intended to be used by file systems that directly add pages to a bio instead of using bio_iov_iter_get_pages(). Reviewed-by:
Jens Axboe <axboe@kernel.dk> Signed-off-by:
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Filipe Manana authored
At btrfs_copy_root(), if the call to btrfs_inc_ref() fails we end up returning without unlocking and releasing our reference on the extent buffer named "cow" we previously allocated with btrfs_alloc_tree_block(). So fix that by unlocking the extent buffer and dropping our reference on it before returning. Fixes: be20aa9d ("Btrfs: Add mount option to turn off data cow") CC: stable@vger.kernel.org # 4.4+ Signed-off-by:
Filipe Manana <fdmanana@suse.com> Reviewed-by:
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Qu Wenruo authored
In read_extent_buffer_pages(), if we failed to lock the page atomically, we just exit with return value 0. This is counter-intuitive, as normally if we can't lock what we need, we would return something like EAGAIN. But that return hides under (wait == WAIT_NONE) branch, which only gets triggered for readahead. And for readahead, if we failed to lock the page, it means the extent buffer is either being read by other thread, or has been read and is under modification. Either way the eb will or has been cached, thus readahead has no need to wait for it. Add comment on this counter-intuitive behavior. Reported-by:
Dan Carpenter <dan.carpenter@oracle.com> Reviewed-by:
Qu Wenruo <wqu@suse.com> Signed-off-by:
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Qu Wenruo authored
This adds the basic RO mount ability for 4K sector size on 64K page system. Currently we only plan to support 4K and 64K page system. Reviewed-by:
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Qu Wenruo authored
In btrfs data page read path, the page status update are handled in two different locations: btrfs_do_read_page() { while (cur <= end) { /* No need to read from disk */ if (HOLE/PREALLOC/INLINE){ memset(); set_extent_uptodate(); continue; } /* Read from disk */ ret = submit_extent_page(end_bio_extent_readpage); } end_bio_extent_readpage() { endio_readpage_uptodate_page_status(); } This is fine for sectorsize == PAGE_SIZE case, as for above loop we should only hit one branch and then exit. But for subpage, there is more work to be done in page status update: - Page Unlock condition Unlike regular page size == sectorsize case, we can no longer just unlock a page. Only the last reader of the page can unlock the page. This means, we can unlock the page either in the while() loop, or in the endio function. - Page uptodate condition Since we have multiple sectors to read for a page, we can only mark the full page uptodate if all sectors are uptodate. To handle both subpage and regular cases, introduce a pair of functions to help handling page status update: - begin_page_read() For regular case, it does nothing. For subpage case, it updates the reader counters so that later end_page_read() can know who is the last one to unlock the page. - end_page_read() This is just endio_readpage_uptodate_page_status() renamed. The original name is a little too long and too specific for endio. The new thing added is the condition for page unlock. Now for subpage data, we unlock the page if we're the last reader. This does not only provide the basis for subpage data read, but also hide the special handling of page read from the main read loop. Also, since we're changing how the page lock is handled, there are two existing error paths where we need to manually unlock the page before calling begin_page_read(). Signed-off-by: -
Qu Wenruo authored
To support subpage sector size, data also need extra info to make sure which sectors in a page are uptodate/dirty/... This patch will make pages for data inodes get btrfs_subpage structure attached, and detached when the page is freed. This patch also slightly changes the timing when set_page_extent_mapped() is called to make sure: - We have page->mapping set page->mapping->host is used to grab btrfs_fs_info, thus we can only call this function after page is mapped to an inode. One call site attaches pages to inode manually, thus we have to modify the timing of set_page_extent_mapped() a bit. - As soon as possible, before other operations Since memory allocation can fail, we have to do extra error handling. Calling set_page_extent_mapped() as soon as possible can simply the error handling for several call sites. The idea is pretty much the same as iomap_page, but with more bitmaps for btrfs specific cases. Currently the plan is to switch iomap if iomap can provide sector aligned write back (only write back dirty sectors, but not the full page, data balance require this feature). So we will stick to btrfs specific bitmap for now. Signed-off-by:
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