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| author |   Zhang Yi <yi.zhang@huawei.com> | 2022-04-24 22:09:35 +0800 |
|---|---|---|
| committer |   Theodore Ts'o <tytso@mit.edu> | 2022-05-17 14:17:40 -0400 |
| commit | 9558cf14e8d2149a8df402b74041a99835801932 (patch) | |
| tree | 248126608f619ff1c351c3c048560cfcd1ecc979 /fs/ext4/inode.c | |
| parent | ext4: fix journal_ioprio mount option handling (diff) | |
| download | linux-dev-9558cf14e8d2149a8df402b74041a99835801932.tar.xz linux-dev-9558cf14e8d2149a8df402b74041a99835801932.zip | |
ext4: add nowait mode for ext4_getblk()
Current ext4_getblk() might sleep if some resources are not valid or
could be race with a concurrent extents modifing procedure. So we
cannot call ext4_getblk() and ext4_map_blocks() to get map blocks in
the atomic context in some fast path (e.g. the upcoming procedure of
getting symlink external block in the RCU context), even if the map
extents have already been check and cached.
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://lore.kernel.org/r/20220424140936.1898920-2-yi.zhang@huawei.com
Diffstat (limited to 'fs/ext4/inode.c')
| -rw-r--r-- | fs/ext4/inode.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 15165c87c915..f7b4787d6679 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -545,12 +545,21 @@ int ext4_map_blocks(handle_t *handle, struct inode *inode, } else { BUG(); } + + if (flags & EXT4_GET_BLOCKS_CACHED_NOWAIT) + return retval; #ifdef ES_AGGRESSIVE_TEST ext4_map_blocks_es_recheck(handle, inode, map, &orig_map, flags); #endif goto found; } + /* + * In the query cache no-wait mode, nothing we can do more if we + * cannot find extent in the cache. + */ + if (flags & EXT4_GET_BLOCKS_CACHED_NOWAIT) + return 0; /* * Try to see if we can get the block without requesting a new @@ -837,10 +846,12 @@ struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode, struct ext4_map_blocks map; struct buffer_head *bh; int create = map_flags & EXT4_GET_BLOCKS_CREATE; + bool nowait = map_flags & EXT4_GET_BLOCKS_CACHED_NOWAIT; int err; ASSERT((EXT4_SB(inode->i_sb)->s_mount_state & EXT4_FC_REPLAY) || handle != NULL || create == 0); + ASSERT(create == 0 || !nowait); map.m_lblk = block; map.m_len = 1; @@ -851,6 +862,9 @@ struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode, if (err < 0) return ERR_PTR(err); + if (nowait) + return sb_find_get_block(inode->i_sb, map.m_pblk); + bh = sb_getblk(inode->i_sb, map.m_pblk); if (unlikely(!bh)) return ERR_PTR(-ENOMEM); |