linux/fs/ext4/ialloc.c, branch v6.17

ext4: limit the maximum folio order

2025-07-15T03:48:15Z

In environments with a page size of 64KB, the maximum size of a folio can reach up to 128MB. Consequently, during the write-back of folios, the 'rsv_blocks' will be overestimated to 1,577, which can make pressure on the journal space where the journal is small. This can easily exceed the limit of a single transaction. Besides, an excessively large folio is meaningless and will instead increase the overhead of traversing the bhs within the folio. Therefore, limit the maximum order of a folio to 2048 filesystem blocks. Reported-by: Naresh Kamboju Reported-by: Joseph Qi Closes: https://lore.kernel.org/linux-ext4/CA+G9fYsyYQ3ZL4xaSg1-Tt5Evto7Zd+hgNWZEa9cQLbahA1+xg@mail.gmail.com/ Signed-off-by: Zhang Yi Tested-by: Joseph Qi Reviewed-by: Jan Kara Link: https://patch.msgid.link/20250707140814.542883-12-yi.zhang@huaweicloud.com Signed-off-by: Theodore Ts'o

ext4: remove sbi argument from ext4_chksum()

2025-05-20T14:31:12Z

Since ext4_chksum() no longer uses its sbi argument, remove it. Signed-off-by: Eric Biggers Reviewed-by: Baokun Li Link: https://patch.msgid.link/20250513053809.699974-2-ebiggers@kernel.org Signed-off-by: Theodore Ts'o

ext4: enable large folio for regular file

2025-05-20T14:31:12Z

Besides fsverity, fscrypt, and the data=journal mode, ext4 now supports large folios for regular files. Enable this feature by default. However, since we cannot change the folio order limitation of mappings on active inodes, setting the journal=data mode via ioctl on an active inode will not take immediate effect in non-delalloc mode. Signed-off-by: Zhang Yi Link: https://patch.msgid.link/20250512063319.3539411-9-yi.zhang@huaweicloud.com Signed-off-by: Theodore Ts'o

mm/migrate: fix sleep in atomic for large folios and buffer heads

2025-04-22T16:16:08Z

The large folio + buffer head noref migration scenarios are being naughty and blocking while holding a spinlock. As a consequence of the pagecache lookup path taking the folio lock this serializes against migration paths, so they can wait for each other. For the private_lock atomic case, a new BH_Migrate flag is introduced which enables the lookup to bail. This allows the critical region of the private_lock on the migration path to be reduced to the way it was before ebdf4de5642fb6 ("mm: migrate: fix reference check race between __find_get_block() and migration"), that is covering the count checks. The scope is always noref migration. Reported-by: kernel test robot Reported-by: syzbot+f3c6fda1297c748a7076@syzkaller.appspotmail.com Closes: https://lore.kernel.org/oe-lkp/202503101536.27099c77-lkp@intel.com Fixes: 3c20917120ce61 ("block/bdev: enable large folio support for large logical block sizes") Reviewed-by: Jan Kara Co-developed-by: Luis Chamberlain Signed-off-by: Davidlohr Bueso Link: https://kdevops.org/ext4/v6.15-rc2.html # [0] Link: https://lore.kernel.org/all/aAAEvcrmREWa1SKF@bombadil.infradead.org/ # [1] Link: https://lore.kernel.org/20250418015921.132400-8-dave@stgolabs.net Tested-by: kdevops@lists.linux.dev # [0] [1] Reviewed-by: Luis Chamberlain Signed-off-by: Christian Brauner

ext4: remove redundant function ext4_has_metadata_csum

2025-03-17T15:19:41Z

Since commit f2b4fa19647e ("ext4: switch to using the crc32c library"), ext4_has_metadata_csum() is just an alias for ext4_has_feature_metadata_csum(). ext4_has_feature_metadata_csum() is generated by EXT4_FEATURE_RO_COMPAT_FUNCS and uses the regular naming convention for checking a single ext4 feature. Therefore, remove ext4_has_metadata_csum() and update all its callers to use ext4_has_feature_metadata_csum() directly. Signed-off-by: Eric Biggers Reviewed-by: Darrick J. Wong Link: https://patch.msgid.link/20250207031335.42637-1-ebiggers@kernel.org Signed-off-by: Theodore Ts'o

ext4: add ext4_emergency_state() helper function

2025-03-13T14:16:34Z

Since both SHUTDOWN and EMERGENCY_RO are emergency states of the ext4 file system, and they are checked in similar locations, we have added a helper function, ext4_emergency_state(), to determine whether the current file system is in one of these two emergency states. Then, replace calls to ext4_forced_shutdown() with ext4_emergency_state() in those functions that could potentially trigger write operations. Signed-off-by: Baokun Li Reviewed-by: Jan Kara Reviewed-by: Zhang Yi Link: https://patch.msgid.link/20250122114130.229709-4-libaokun@huaweicloud.com Signed-off-by: Theodore Ts'o

ext4: Don't set EXT4_STATE_MAY_INLINE_DATA for ea inodes

2025-03-13T13:57:19Z

Setting the EXT4_STATE_MAY_INLINE_DATA flag for ea inodes is meaningless because ea inodes do not use functions like ext4_write_begin(). Signed-off-by: Julian Sun Reviewed-by: Jan Kara Link: https://patch.msgid.link/20250107044702.1836852-3-sunjunchao2870@gmail.com Signed-off-by: Theodore Ts'o

ext4: fix race in buffer_head read fault injection

2024-11-13T04:54:14Z

When I enabled ext4 debug for fault injection testing, I encountered the following warning: EXT4-fs error (device sda): ext4_read_inode_bitmap:201: comm fsstress: Cannot read inode bitmap - block_group = 8, inode_bitmap = 1051 WARNING: CPU: 0 PID: 511 at fs/buffer.c:1181 mark_buffer_dirty+0x1b3/0x1d0 The root cause of the issue lies in the improper implementation of ext4's buffer_head read fault injection. The actual completion of buffer_head read and the buffer_head fault injection are not atomic, which can lead to the uptodate flag being cleared on normally used buffer_heads in race conditions. [CPU0] [CPU1] [CPU2] ext4_read_inode_bitmap ext4_read_bh() ext4_read_inode_bitmap if (buffer_uptodate(bh)) return bh jbd2_journal_commit_transaction __jbd2_journal_refile_buffer __jbd2_journal_unfile_buffer __jbd2_journal_temp_unlink_buffer ext4_simulate_fail_bh() clear_buffer_uptodate mark_buffer_dirty WARN_ON_ONCE(!buffer_uptodate(bh)) The best approach would be to perform fault injection in the IO completion callback function, rather than after IO completion. However, the IO completion callback function cannot get the fault injection code in sb. Fix it by passing the result of fault injection into the bh read function, we simulate faults within the bh read function itself. This requires adding an extra parameter to the bh read functions that need fault injection. Fixes: 46f870d690fe ("ext4: simulate various I/O and checksum errors when reading metadata") Signed-off-by: Long Li Link: https://patch.msgid.link/20240906091746.510163-1-leo.lilong@huawei.com Signed-off-by: Theodore Ts'o

ext4: check buffer_verified in advance to avoid unneeded ext4_get_group_info()

2024-09-04T02:12:16Z

Check buffer_verified in advance to avoid unneeded ext4_get_group_info(). This could be a simple cleanup as compiler may handle this. Signed-off-by: Kemeng Shi Link: https://patch.msgid.link/20240820132234.2759926-8-shikemeng@huaweicloud.com Signed-off-by: Theodore Ts'o

ext4: remove unneeded NULL check of buffer_head in ext4_mark_inode_used()

2024-09-04T02:12:16Z

If gdp from ext4_get_group_desc() is not NULL, then returned group_desc_bh won't be NULL either. Remove check of group_desc_bh and only check returned gdp from ext4_get_group_desc() like how other callers do. Signed-off-by: Kemeng Shi Link: https://patch.msgid.link/20240820132234.2759926-7-shikemeng@huaweicloud.com Signed-off-by: Theodore Ts'o