Message ID | 20100810232321.0eb72247.toshi.okajima@jp.fujitsu.com |
---|---|
State | New, archived |
Headers | show |
On 2010-08-10, at 10:23, Toshiyuki Okajima wrote: > Table. the max file size which we can write or seek > at each filesystem feature tuning and file flag setting > +===============================+===============================+ > | | | > | !EXT4_EXTENTS_FL | EXT4_EXTETNS_FL | > | | | > +-------------------------------+-------------------------------+ > | write: 2194719883264 | write: -------------- | > | seek: 2199023251456 | seek: -------------- | > +-------------------------------+-------------------------------+ > | write: 4402345721856 | write: 17592186044415 | > | seek: 17592186044415 | seek: 17592186044415 | > +-------------------------------+-------------------------------+ Interesting. The 2TB vs. 4TB difference for block-mapped files is due to the removal of the 2^32 sectors limit imposed by i_blocks, and is not strictly related to extents. > +loff_t ext4_llseek(struct file *file, loff_t offset, int origin) > +{ > + struct inode *inode = file->f_mapping->host; > + loff_t maxbytes; > + > + mutex_lock(&inode->i_mutex); > + if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) > + maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes; > + else > + maxbytes = inode->i_sb->s_maxbytes; This part doesn't really have to be under i_mutex. Otherwise, the patch looks reasonable. > + switch (origin) { > + case SEEK_END: > + offset += inode->i_size; > + break; > + case SEEK_CUR: > + if (offset == 0) { > + mutex_unlock(&inode->i_mutex); > + return file->f_pos; > + } > + offset += file->f_pos; > + break; > + } > + > + if (offset < 0 || offset > maxbytes) { > + mutex_unlock(&inode->i_mutex); > + return -EINVAL; > + } > + > + if (offset != file->f_pos) { > + file->f_pos = offset; > + file->f_version = 0; > + } > + mutex_unlock(&inode->i_mutex); > + > + return offset; > +} It's too bad that we have to duplicate the whole generic_file_llseek() code here, but I don't think there is a better solution. However, it is worthwhile to add a comment to this function like: /* copied from generic_file_llseek() to handle both block-mapped and * extent-mapped maxbytes values. Should otherwise be identical. */ Cheers, Andreas -- Andreas Dilger Lustre Technical Lead Oracle Corporation Canada Inc. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi. (2010/08/10 15:35), Andreas Dilger wrote: > > On 2010-08-10, at 10:23, Toshiyuki Okajima wrote: <snip> >> +loff_t ext4_llseek(struct file *file, loff_t offset, int origin) >> +{ >> + struct inode *inode = file->f_mapping->host; >> + loff_t maxbytes; >> + >> + mutex_lock(&inode->i_mutex); >> + if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) >> + maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes; >> + else >> + maxbytes = inode->i_sb->s_maxbytes; > > This part doesn't really have to be under i_mutex. Otherwise, the patch looks reasonable. OK. > >> + switch (origin) { >> + case SEEK_END: >> + offset += inode->i_size; >> + break; >> + case SEEK_CUR: >> + if (offset == 0) { >> + mutex_unlock(&inode->i_mutex); >> + return file->f_pos; >> + } >> + offset += file->f_pos; >> + break; >> + } >> + >> + if (offset< 0 || offset> maxbytes) { >> + mutex_unlock(&inode->i_mutex); >> + return -EINVAL; >> + } >> + >> + if (offset != file->f_pos) { >> + file->f_pos = offset; >> + file->f_version = 0; >> + } >> + mutex_unlock(&inode->i_mutex); >> + >> + return offset; >> +} > > It's too bad that we have to duplicate the whole generic_file_llseek() code here, but I don't think there is a better solution. However, it is worthwhile to add a comment to this function like: > > /* copied from generic_file_llseek() to handle both block-mapped and > * extent-mapped maxbytes values. Should otherwise be identical. */ I understand it. I apply your comments and then rebuild my patch. Immediately I'll send it. Thanks, Toshiyuki Okajima -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
================================================================================ Subject: [PATCH] ext4: create own llseek function to handle the max file size correctly. From: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com> If the file has no EXT4_EXTENTS_FL flag, the maximum size which can be written (write systemcall) is different from the maximum size which can be seeked (lseek systemcall). For example, the following 2 cases show us the differences: #1: mkfs.ext3 <dev>; mount -t ext4 <dev> #2: mkfs.ext3 <dev>; tune2fs -Oextent,huge_file <dev>; mount -t ext4 <dev> Table. the max file size which we can write or seek at each filesystem feature tuning and file flag setting +============+===============================+===============================+ | \ File flag| | | | \ | !EXT4_EXTENTS_FL | EXT4_EXTETNS_FL | |case \| | | +------------+-------------------------------+-------------------------------+ | #1 | write: 2194719883264 | write: -------------- | | | seek: 2199023251456 | seek: -------------- | +------------+-------------------------------+-------------------------------+ | #2 | write: 4402345721856 | write: 17592186044415 | | | seek: 17592186044415 | seek: 17592186044415 | +------------+-------------------------------+-------------------------------+ The differences exist because ext4 has 2 max-file-size (sb->s_maxbytes, EXT4_SB(sb)->s_bitmap_maxbytes) although generic_file_llseek uses only sb->s_maxbytes. (llseek of ext4_file_operations is generic_file_llseek.) Therefore we create own llseek function which uses 2 max-file-size. The new own function originates from generic_file_llseek_nolocked(). If the file flag, "EXT4_EXTENTS_FL" is not set, the function alters inode->i_sb->s_maxbytes into EXT4_SB(inode->i_sb)->s_bitmap_maxbytes. Signed-off-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com> --- fs/ext4/dir.c | 2 +- fs/ext4/ext4.h | 1 + fs/ext4/file.c | 39 ++++++++++++++++++++++++++++++++++++++- 3 files changed, 40 insertions(+), 2 deletions(-) diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c index ea5e6cb..62c9bba 100644 --- a/fs/ext4/dir.c +++ b/fs/ext4/dir.c @@ -39,7 +39,7 @@ static int ext4_release_dir(struct inode *inode, struct file *filp); const struct file_operations ext4_dir_operations = { - .llseek = generic_file_llseek, + .llseek = ext4_llseek, .read = generic_read_dir, .readdir = ext4_readdir, /* we take BKL. needed?*/ .unlocked_ioctl = ext4_ioctl, diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 19a4de5..e7050cd 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -1870,6 +1870,7 @@ extern const struct file_operations ext4_dir_operations; /* file.c */ extern const struct inode_operations ext4_file_inode_operations; extern const struct file_operations ext4_file_operations; +extern loff_t ext4_llseek(struct file *file, loff_t offset, int origin); /* namei.c */ extern const struct inode_operations ext4_dir_inode_operations; diff --git a/fs/ext4/file.c b/fs/ext4/file.c index 5313ae4..f2e2d57 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -129,8 +129,45 @@ static int ext4_file_open(struct inode * inode, struct file * filp) return dquot_file_open(inode, filp); } +loff_t ext4_llseek(struct file *file, loff_t offset, int origin) +{ + struct inode *inode = file->f_mapping->host; + loff_t maxbytes; + + mutex_lock(&inode->i_mutex); + if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) + maxbytes = EXT4_SB(inode->i_sb)->s_bitmap_maxbytes; + else + maxbytes = inode->i_sb->s_maxbytes; + switch (origin) { + case SEEK_END: + offset += inode->i_size; + break; + case SEEK_CUR: + if (offset == 0) { + mutex_unlock(&inode->i_mutex); + return file->f_pos; + } + offset += file->f_pos; + break; + } + + if (offset < 0 || offset > maxbytes) { + mutex_unlock(&inode->i_mutex); + return -EINVAL; + } + + if (offset != file->f_pos) { + file->f_pos = offset; + file->f_version = 0; + } + mutex_unlock(&inode->i_mutex); + + return offset; +} + const struct file_operations ext4_file_operations = { - .llseek = generic_file_llseek, + .llseek = ext4_llseek, .read = do_sync_read, .write = do_sync_write, .aio_read = generic_file_aio_read,