On 6/20/22 21:16, gregkh@xxxxxxxxxxxxxxxxxxx wrote:
>
> The patch below does not apply to the 5.10-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@xxxxxxxxxxxxxxx>.
>
> thanks,
>
> greg k-h
Greg,
I sent you the backported patch in reply to this email.
Thanks !
>
> ------------------ original commit in Linus's tree ------------------
>
> From c1c1204c0d0c1dccc1310b9277fb2bd8b663d8fe Mon Sep 17 00:00:00 2001
> From: Damien Le Moal <damien.lemoal@xxxxxxxxxxxxxxxxxx>
> Date: Mon, 23 May 2022 16:29:10 +0900
> Subject: [PATCH] zonefs: fix zonefs_iomap_begin() for reads
>
> If a readahead is issued to a sequential zone file with an offset
> exactly equal to the current file size, the iomap type is set to
> IOMAP_UNWRITTEN, which will prevent an IO, but the iomap length is
> calculated as 0. This causes a WARN_ON() in iomap_iter():
>
> [17309.548939] WARNING: CPU: 3 PID: 2137 at fs/iomap/iter.c:34 iomap_iter+0x9cf/0xe80
> [...]
> [17309.650907] RIP: 0010:iomap_iter+0x9cf/0xe80
> [...]
> [17309.754560] Call Trace:
> [17309.757078] <TASK>
> [17309.759240] ? lock_is_held_type+0xd8/0x130
> [17309.763531] iomap_readahead+0x1a8/0x870
> [17309.767550] ? iomap_read_folio+0x4c0/0x4c0
> [17309.771817] ? lockdep_hardirqs_on_prepare+0x400/0x400
> [17309.778848] ? lock_release+0x370/0x750
> [17309.784462] ? folio_add_lru+0x217/0x3f0
> [17309.790220] ? reacquire_held_locks+0x4e0/0x4e0
> [17309.796543] read_pages+0x17d/0xb60
> [17309.801854] ? folio_add_lru+0x238/0x3f0
> [17309.807573] ? readahead_expand+0x5f0/0x5f0
> [17309.813554] ? policy_node+0xb5/0x140
> [17309.819018] page_cache_ra_unbounded+0x27d/0x450
> [17309.825439] filemap_get_pages+0x500/0x1450
> [17309.831444] ? filemap_add_folio+0x140/0x140
> [17309.837519] ? lock_is_held_type+0xd8/0x130
> [17309.843509] filemap_read+0x28c/0x9f0
> [17309.848953] ? zonefs_file_read_iter+0x1ea/0x4d0 [zonefs]
> [17309.856162] ? trace_contention_end+0xd6/0x130
> [17309.862416] ? __mutex_lock+0x221/0x1480
> [17309.868151] ? zonefs_file_read_iter+0x166/0x4d0 [zonefs]
> [17309.875364] ? filemap_get_pages+0x1450/0x1450
> [17309.881647] ? __mutex_unlock_slowpath+0x15e/0x620
> [17309.888248] ? wait_for_completion_io_timeout+0x20/0x20
> [17309.895231] ? lock_is_held_type+0xd8/0x130
> [17309.901115] ? lock_is_held_type+0xd8/0x130
> [17309.906934] zonefs_file_read_iter+0x356/0x4d0 [zonefs]
> [17309.913750] new_sync_read+0x2d8/0x520
> [17309.919035] ? __x64_sys_lseek+0x1d0/0x1d0
>
> Furthermore, this causes iomap_readahead() to loop forever as
> iomap_readahead_iter() always returns 0, making no progress.
>
> Fix this by treating reads after the file size as access to holes,
> setting the iomap type to IOMAP_HOLE, the iomap addr to IOMAP_NULL_ADDR
> and using the length argument as is for the iomap length. To simplify
> the code with this change, zonefs_iomap_begin() is split into the read
> variant, zonefs_read_iomap_begin() and zonefs_read_iomap_ops, and the
> write variant, zonefs_write_iomap_begin() and zonefs_write_iomap_ops.
>
> Reported-by: Jorgen Hansen <Jorgen.Hansen@xxxxxxx>
> Fixes: 8dcc1a9d90c1 ("fs: New zonefs file system")
> Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxxxxxxxxxxxxx>
> Reviewed-by: Christoph Hellwig <hch@xxxxxx>
> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@xxxxxxx>
> Reviewed-by: Jorgen Hansen <Jorgen.Hansen@xxxxxxx>
>
> diff --git a/fs/zonefs/super.c b/fs/zonefs/super.c
> index 123464d2145a..053299758deb 100644
> --- a/fs/zonefs/super.c
> +++ b/fs/zonefs/super.c
> @@ -110,15 +110,51 @@ static inline void zonefs_i_size_write(struct inode *inode, loff_t isize)
> }
> }
>
> -static int zonefs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> - unsigned int flags, struct iomap *iomap,
> - struct iomap *srcmap)
> +static int zonefs_read_iomap_begin(struct inode *inode, loff_t offset,
> + loff_t length, unsigned int flags,
> + struct iomap *iomap, struct iomap *srcmap)
> {
> struct zonefs_inode_info *zi = ZONEFS_I(inode);
> struct super_block *sb = inode->i_sb;
> loff_t isize;
>
> - /* All I/Os should always be within the file maximum size */
> + /*
> + * All blocks are always mapped below EOF. If reading past EOF,
> + * act as if there is a hole up to the file maximum size.
> + */
> + mutex_lock(&zi->i_truncate_mutex);
> + iomap->bdev = inode->i_sb->s_bdev;
> + iomap->offset = ALIGN_DOWN(offset, sb->s_blocksize);
> + isize = i_size_read(inode);
> + if (iomap->offset >= isize) {
> + iomap->type = IOMAP_HOLE;
> + iomap->addr = IOMAP_NULL_ADDR;
> + iomap->length = length;
> + } else {
> + iomap->type = IOMAP_MAPPED;
> + iomap->addr = (zi->i_zsector << SECTOR_SHIFT) + iomap->offset;
> + iomap->length = isize - iomap->offset;
> + }
> + mutex_unlock(&zi->i_truncate_mutex);
> +
> + trace_zonefs_iomap_begin(inode, iomap);
> +
> + return 0;
> +}
> +
> +static const struct iomap_ops zonefs_read_iomap_ops = {
> + .iomap_begin = zonefs_read_iomap_begin,
> +};
> +
> +static int zonefs_write_iomap_begin(struct inode *inode, loff_t offset,
> + loff_t length, unsigned int flags,
> + struct iomap *iomap, struct iomap *srcmap)
> +{
> + struct zonefs_inode_info *zi = ZONEFS_I(inode);
> + struct super_block *sb = inode->i_sb;
> + loff_t isize;
> +
> + /* All write I/Os should always be within the file maximum size */
> if (WARN_ON_ONCE(offset + length > zi->i_max_size))
> return -EIO;
>
> @@ -128,7 +164,7 @@ static int zonefs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> * operation.
> */
> if (WARN_ON_ONCE(zi->i_ztype == ZONEFS_ZTYPE_SEQ &&
> - (flags & IOMAP_WRITE) && !(flags & IOMAP_DIRECT)))
> + !(flags & IOMAP_DIRECT)))
> return -EIO;
>
> /*
> @@ -137,47 +173,44 @@ static int zonefs_iomap_begin(struct inode *inode, loff_t offset, loff_t length,
> * write pointer) and unwriten beyond.
> */
> mutex_lock(&zi->i_truncate_mutex);
> + iomap->bdev = inode->i_sb->s_bdev;
> + iomap->offset = ALIGN_DOWN(offset, sb->s_blocksize);
> + iomap->addr = (zi->i_zsector << SECTOR_SHIFT) + iomap->offset;
> isize = i_size_read(inode);
> - if (offset >= isize)
> + if (iomap->offset >= isize) {
> iomap->type = IOMAP_UNWRITTEN;
> - else
> + iomap->length = zi->i_max_size - iomap->offset;
> + } else {
> iomap->type = IOMAP_MAPPED;
> - if (flags & IOMAP_WRITE)
> - length = zi->i_max_size - offset;
> - else
> - length = min(length, isize - offset);
> + iomap->length = isize - iomap->offset;
> + }
> mutex_unlock(&zi->i_truncate_mutex);
>
> - iomap->offset = ALIGN_DOWN(offset, sb->s_blocksize);
> - iomap->length = ALIGN(offset + length, sb->s_blocksize) - iomap->offset;
> - iomap->bdev = inode->i_sb->s_bdev;
> - iomap->addr = (zi->i_zsector << SECTOR_SHIFT) + iomap->offset;
> -
> trace_zonefs_iomap_begin(inode, iomap);
>
> return 0;
> }
>
> -static const struct iomap_ops zonefs_iomap_ops = {
> - .iomap_begin = zonefs_iomap_begin,
> +static const struct iomap_ops zonefs_write_iomap_ops = {
> + .iomap_begin = zonefs_write_iomap_begin,
> };
>
> static int zonefs_read_folio(struct file *unused, struct folio *folio)
> {
> - return iomap_read_folio(folio, &zonefs_iomap_ops);
> + return iomap_read_folio(folio, &zonefs_read_iomap_ops);
> }
>
> static void zonefs_readahead(struct readahead_control *rac)
> {
> - iomap_readahead(rac, &zonefs_iomap_ops);
> + iomap_readahead(rac, &zonefs_read_iomap_ops);
> }
>
> /*
> * Map blocks for page writeback. This is used only on conventional zone files,
> * which implies that the page range can only be within the fixed inode size.
> */
> -static int zonefs_map_blocks(struct iomap_writepage_ctx *wpc,
> - struct inode *inode, loff_t offset)
> +static int zonefs_write_map_blocks(struct iomap_writepage_ctx *wpc,
> + struct inode *inode, loff_t offset)
> {
> struct zonefs_inode_info *zi = ZONEFS_I(inode);
>
> @@ -191,12 +224,12 @@ static int zonefs_map_blocks(struct iomap_writepage_ctx *wpc,
> offset < wpc->iomap.offset + wpc->iomap.length)
> return 0;
>
> - return zonefs_iomap_begin(inode, offset, zi->i_max_size - offset,
> - IOMAP_WRITE, &wpc->iomap, NULL);
> + return zonefs_write_iomap_begin(inode, offset, zi->i_max_size - offset,
> + IOMAP_WRITE, &wpc->iomap, NULL);
> }
>
> static const struct iomap_writeback_ops zonefs_writeback_ops = {
> - .map_blocks = zonefs_map_blocks,
> + .map_blocks = zonefs_write_map_blocks,
> };
>
> static int zonefs_writepage(struct page *page, struct writeback_control *wbc)
> @@ -226,7 +259,8 @@ static int zonefs_swap_activate(struct swap_info_struct *sis,
> return -EINVAL;
> }
>
> - return iomap_swapfile_activate(sis, swap_file, span, &zonefs_iomap_ops);
> + return iomap_swapfile_activate(sis, swap_file, span,
> + &zonefs_read_iomap_ops);
> }
>
> static const struct address_space_operations zonefs_file_aops = {
> @@ -647,7 +681,7 @@ static vm_fault_t zonefs_filemap_page_mkwrite(struct vm_fault *vmf)
>
> /* Serialize against truncates */
> filemap_invalidate_lock_shared(inode->i_mapping);
> - ret = iomap_page_mkwrite(vmf, &zonefs_iomap_ops);
> + ret = iomap_page_mkwrite(vmf, &zonefs_write_iomap_ops);
> filemap_invalidate_unlock_shared(inode->i_mapping);
>
> sb_end_pagefault(inode->i_sb);
> @@ -899,7 +933,7 @@ static ssize_t zonefs_file_dio_write(struct kiocb *iocb, struct iov_iter *from)
> if (append)
> ret = zonefs_file_dio_append(iocb, from);
> else
> - ret = iomap_dio_rw(iocb, from, &zonefs_iomap_ops,
> + ret = iomap_dio_rw(iocb, from, &zonefs_write_iomap_ops,
> &zonefs_write_dio_ops, 0, NULL, 0);
> if (zi->i_ztype == ZONEFS_ZTYPE_SEQ &&
> (ret > 0 || ret == -EIOCBQUEUED)) {
> @@ -948,7 +982,7 @@ static ssize_t zonefs_file_buffered_write(struct kiocb *iocb,
> if (ret <= 0)
> goto inode_unlock;
>
> - ret = iomap_file_buffered_write(iocb, from, &zonefs_iomap_ops);
> + ret = iomap_file_buffered_write(iocb, from, &zonefs_write_iomap_ops);
> if (ret > 0)
> iocb->ki_pos += ret;
> else if (ret == -EIO)
> @@ -1041,7 +1075,7 @@ static ssize_t zonefs_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
> goto inode_unlock;
> }
> file_accessed(iocb->ki_filp);
> - ret = iomap_dio_rw(iocb, to, &zonefs_iomap_ops,
> + ret = iomap_dio_rw(iocb, to, &zonefs_read_iomap_ops,
> &zonefs_read_dio_ops, 0, NULL, 0);
> } else {
> ret = generic_file_read_iter(iocb, to);
>
--
Damien Le Moal
Western Digital Research
