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Wed, 4 Dec 2024 12:16:45 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id zezGEC1IUGcEIwAAD6G6ig (envelope-from ); Wed, 04 Dec 2024 12:16:45 +0000 Received: by quack3.suse.cz (Postfix, from userid 1000) id E90E6A0918; Wed, 4 Dec 2024 13:16:44 +0100 (CET) Date: Wed, 4 Dec 2024 13:16:44 +0100 From: Jan Kara To: Zhang Yi Cc: linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu, adilger.kernel@dilger.ca, jack@suse.cz, ritesh.list@gmail.com, hch@infradead.org, djwong@kernel.org, david@fromorbit.com, zokeefe@google.com, yi.zhang@huawei.com, chengzhihao1@huawei.com, yukuai3@huawei.com, yangerkun@huawei.com Subject: Re: [PATCH 11/27] ext4: use reserved metadata blocks when splitting extent on endio Message-ID: <20241204121644.gmflmc4u3u34vltt@quack3> References: <20241022111059.2566137-1-yi.zhang@huaweicloud.com> <20241022111059.2566137-12-yi.zhang@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241022111059.2566137-12-yi.zhang@huaweicloud.com> X-Rspamd-Queue-Id: 5798F21162 X-Spam-Level: X-Spamd-Result: default: False [-2.51 / 50.00]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; MID_RHS_NOT_FQDN(0.50)[]; R_DKIM_ALLOW(-0.20)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; RCVD_COUNT_THREE(0.00)[3]; FUZZY_BLOCKED(0.00)[rspamd.com]; ARC_NA(0.00)[]; RCPT_COUNT_TWELVE(0.00)[16]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; MIME_TRACE(0.00)[0:+]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; TO_MATCH_ENVRCPT_ALL(0.00)[]; TO_DN_SOME(0.00)[]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; RCVD_TLS_LAST(0.00)[]; TAGGED_RCPT(0.00)[]; MISSING_XM_UA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; FREEMAIL_CC(0.00)[vger.kernel.org,mit.edu,dilger.ca,suse.cz,gmail.com,infradead.org,kernel.org,fromorbit.com,google.com,huawei.com]; DKIM_TRACE(0.00)[suse.cz:+]; DBL_BLOCKED_OPENRESOLVER(0.00)[huawei.com:email,suse.cz:dkim,suse.cz:email,imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns,suse.com:email] X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Action: no action X-Spam-Score: -2.51 X-Spam-Flag: NO On Tue 22-10-24 19:10:42, Zhang Yi wrote: > From: Zhang Yi > > When performing buffered writes, we may need to split and convert an > unwritten extent into a written one during the end I/O process. However, > we do not reserve space specifically for these metadata changes, we only > reserve 2% of space or 4096 blocks. To address this, we use > EXT4_GET_BLOCKS_PRE_IO to potentially split extents in advance and > EXT4_GET_BLOCKS_METADATA_NOFAIL to utilize reserved space if necessary. > > These two approaches can reduce the likelihood of running out of space > and losing data. However, these methods are merely best efforts, we > could still run out of space, and there is not much difference between > converting an extent during the writeback process and the end I/O > process, it won't increase the rick of losing data if we postpone the > conversion. > > Therefore, also use EXT4_GET_BLOCKS_METADATA_NOFAIL in > ext4_convert_unwritten_extents_endio() to prepare for the buffered I/O > iomap conversion, which may perform extent conversion during the end I/O > process. > > Signed-off-by: Zhang Yi Yeah, I agree. Feel free to add: Reviewed-by: Jan Kara Honza > --- > fs/ext4/extents.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c > index d5067d5aa449..33bc2cc5aff4 100644 > --- a/fs/ext4/extents.c > +++ b/fs/ext4/extents.c > @@ -3767,6 +3767,8 @@ ext4_convert_unwritten_extents_endio(handle_t *handle, struct inode *inode, > * illegal. > */ > if (ee_block != map->m_lblk || ee_len > map->m_len) { > + int flags = EXT4_GET_BLOCKS_CONVERT | > + EXT4_GET_BLOCKS_METADATA_NOFAIL; > #ifdef CONFIG_EXT4_DEBUG > ext4_warning(inode->i_sb, "Inode (%ld) finished: extent logical block %llu," > " len %u; IO logical block %llu, len %u", > @@ -3774,7 +3776,7 @@ ext4_convert_unwritten_extents_endio(handle_t *handle, struct inode *inode, > (unsigned long long)map->m_lblk, map->m_len); > #endif > path = ext4_split_convert_extents(handle, inode, map, path, > - EXT4_GET_BLOCKS_CONVERT, NULL); > + flags, NULL); > if (IS_ERR(path)) > return path; > > -- > 2.46.1 > -- Jan Kara SUSE Labs, CR