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([176.13.144.22]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-385ccd80435sm17436742f8f.100.2024.12.04.01.02.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Dec 2024 01:02:30 -0800 (PST) From: Max Brener To: tytso@mit.edu Cc: adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, Max Brener Subject: [PATCH v3] ext4: Optimization of no-op ext4_truncate triggers Date: Wed, 4 Dec 2024 11:02:25 +0200 Message-ID: <20241204090225.721618-1-linmaxi@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Closes: https://bugzilla.kernel.org/show_bug.cgi?id=3D219306 v2: https://lore.kernel.org/lkml/20241001082459.14580-1-linmaxi@gmail.com/T/ OR https://patchwork.ozlabs.org/project/linux-ext4/patch/20241016111624.5229-= 1-linmaxi@gmail.com/ Fix from last version: Clear the EXT4_STATE_TRUNCATED flag at ext4_mb_new_blocks() in order to make sure that every attempt to allocate new blocks, will result in resetti= ng the 'truncated' state of the inode. Why is this needed? We want the ability to truncate preallocated blocks of = an inode by using ext4_truncate(). However, when ftruncate is called from the vfs, t= he call is blocked (at ext4_setattr()) when used on already-truncated inodes. We wa= nt that call to be blocked only if the truncate call is redundant (meanning there is nothing there to truncate). --- fs/ext4/ext4.h | 1 + fs/ext4/extents.c | 5 +++++ fs/ext4/inode.c | 6 +++++- fs/ext4/mballoc.c | 5 +++++ 4 files changed, 16 insertions(+), 1 deletion(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 44b0d418143c..032e51f2a92b 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -1915,6 +1915,7 @@ enum { EXT4_STATE_VERITY_IN_PROGRESS, /* building fs-verity Merkle tree */ EXT4_STATE_FC_COMMITTING, /* Fast commit ongoing */ EXT4_STATE_ORPHAN_FILE, /* Inode orphaned in orphan file */ + EXT4_STATE_TRUNCATED, /* Inode is truncated */ }; =20 #define EXT4_INODE_BIT_FNS(name, field, offset) \ diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index 34e25eee6521..531fa0f2ccd3 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -4782,6 +4782,11 @@ long ext4_fallocate(struct file *file, int mode, lof= f_t offset, loff_t len) ret =3D ext4_zero_range(file, offset, len, mode); goto exit; } + + if (mode & FALLOC_FL_KEEP_SIZE) { + ext4_clear_inode_state(inode, EXT4_STATE_TRUNCATED); + } + trace_ext4_fallocate_enter(inode, offset, len, mode); lblk =3D offset >> blkbits; =20 diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 54bdd4884fe6..cbdad3253920 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4193,6 +4193,8 @@ int ext4_truncate(struct inode *inode) if (IS_SYNC(inode)) ext4_handle_sync(handle); =20 + ext4_set_inode_state(inode, EXT4_STATE_TRUNCATED); + out_stop: /* * If this was a simple ftruncate() and the file will remain alive, @@ -5492,7 +5494,9 @@ int ext4_setattr(struct mnt_idmap *idmap, struct dent= ry *dentry, * Call ext4_truncate() even if i_size didn't change to * truncate possible preallocated blocks. */ - if (attr->ia_size <=3D oldsize) { + if (attr->ia_size < oldsize || + (attr->ia_size =3D=3D oldsize && + !ext4_test_inode_state(inode, EXT4_STATE_TRUNCATED))) { rc =3D ext4_truncate(inode); if (rc) error =3D rc; diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index d73e38323879..4f0dbd53b3df 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -6149,6 +6149,11 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle, sb =3D ar->inode->i_sb; sbi =3D EXT4_SB(sb); =20 + /* Once there is an attempt to allocate new blocks, + * the inode is no longer considered truncated. + */ + ext4_clear_inode_state(ar->inode, EXT4_STATE_TRUNCATED); + trace_ext4_request_blocks(ar); if (sbi->s_mount_state & EXT4_FC_REPLAY) return ext4_mb_new_blocks_simple(ar, errp); --=20 2.43.0